diff --git a/.travis.yml b/.travis.yml
index 8bf5226..a0b6549 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,14 +1,14 @@
 language: php
 
-php: ["5.3", "5.4", "5.5", "5.6", "hhvm"]
+php: ["5.3", "5.4", "5.5", "5.6", "hhvm", "hhvm-nightly"]
 
 matrix:
-    allow_failures: [{"php": "5.6"}, {"php": "hhvm"}]
+    allow_failures: [{"php": "hhvm"}, {"php": "hhvm-nightly"}]
     fast_finish: true
 
 env:
   global:
-    - ARCHER_PUBLISH_VERSION=5.5
+    - ARCHER_PUBLISH_VERSION=5.6
     - secure: "O/QlJbj5sRzjQifZBowuwIlBk9g1Ig6kGULzAdx0oXHEGgurH47IZcHkDBHvmqaAABXtE4K3jrd3cuX6Vm/7GiRThA5dYYMt40qnJdLEt8HlhrnmmlSIJQioS6l6x3UbBC3xvaeQYZIXgkyUjFSWVWsACXjYJwqtXaCuXXAvyNQ="
 
 install:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6570281..4772c69 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Isolator Changelog
 
+### 3.0.0 (2014-10-08)
+
+* **[BC]** Removed `Isolator::getIsolator()` and `resetIsolator()`
+* **[BC]** Removed `Isolator::className()` (the full class name is now always `Icecave\Isolator\Isolator`)
+* **[FIXED]** Calling functions with variable arguments now works correctly in PHP 5.6
+* **[NEW]** Added `Isolator::set()`
+* **[IMPROVED]** Code is now generated via a custom autoloader, and then cached, providing a massive performance improvement
+* **[IMRPOVED]** Several micro-optimisations to invocation of function-like language constructs
+
+While this release contains several backwards compatibility breaks, the `Isolator` class itself still behaves as per the
+examples given in the README file of v2.3.0.
+
 ### 2.3.0 (2014-08-12)
 
 * **[NEW]** Added support for isolation of the `new` operator
@@ -16,7 +28,7 @@
 
 ### 2.1.2 (2013-04-04)
 
-* **[FIX]** Return values of isolated `include/require[_once]` calls are now propagated correctly
+* **[FIXED]** Return values of isolated `include/require[_once]` calls are now propagated correctly
 * **[NEW]** Integrated `icecave/archer` (previously `icecave/testing`)
 
 ### 2.1.1 (2013-01-13)
diff --git a/README.md b/README.md
index e200b66..a42179c 100644
--- a/README.md
+++ b/README.md
@@ -68,8 +68,8 @@ class MyDocument
 }
 ```
 
-MyDocument now takes an instance of `Isolator` in it's constructor. It would be a pain - and unnecessary - to specify
-the `Isolator` instance every time you construct an object in your production code, so a shared instance is made
+`MyDocument` now takes an instance of `Isolator` in it's constructor. It would be a pain - and unnecessary - to create a
+new `Isolator` instance every time you construct an object in your production code, so a shared instance is made
 accessible using the `Isolator::get()` method. If a non-null value is passed to `Isolator::get()` it is returned
 unchanged, allowing you to replace the isolator when necessary.
 
@@ -81,16 +81,14 @@ test suite below.
 for mocking. Phake provides a more flexible alternative to PHPUnit's built-in mock objects.*
 
 ```php
-use Icecave\Isolator\Isolator;
-
 class MyDocumentTest extends PHPUnit_Framework_TestCase
 {
     public function setUp()
     {
         // First a mocked isolator instance is created ...
-        $this->isolator = Phake::mock(Isolator::className());
+        $this->isolator = Phake::mock('Icecave\Isolator\Isolator');
 
-        // That isolator instance is provided to the MyDocument instance
+        // That isolator instance is given to the MyDocument instance
         // that is to be tested ...
         $this->myDocument = new MyDocument('foo.txt', $this->isolator);
     }
@@ -118,9 +116,9 @@ class MyDocumentTest extends PHPUnit_Framework_TestCase
 
 The test verifies the behavior of the `MyDocument` class completely, without requiring any disk access.
 
-Using an isolator is most helpful when testing code that uses global functions which maintain global state or utilize
-external resources such as databases, filesystems, etc. It is usually unnecessary to mock out deterministic functions
-such as `strlen()`, for example.
+Using an isolator is most helpful when testing code that uses functions which maintain global state or utilize external
+resources such as databases, filesystems, etc. It is usually unnecessary to mock out deterministic functions such as
+`strlen()`, for example.
 
 ## Isolator Trait
 
@@ -145,7 +143,6 @@ class MyDocument
     }
 
     protected $filename;
-    protected $isolator;
 }
 ```
 
@@ -163,9 +160,15 @@ class MyDocument
 
 Several of PHP's core global functions have some peculiarities and inconsitencies in the way they are defined.
 **Isolator** attempts to accomodate such inconsistencies when possible, but may have issues with some native C functions
-for which parameter reflection information is non-standard or incorrect.
+for which parameter reflection information is non-standard or incorrect. These issues seem to be largely rectified as of
+PHP 5.6.
+
+## Contact us
+
+* Follow [@IcecaveStudios](https://twitter.com/IcecaveStudios) on Twitter
+* Visit the [Icecave Studios website](http://icecave.com.au)
 
 <!-- references -->
-[Build Status]: http://img.shields.io/travis/IcecaveStudios/isolator/develop.svg
-[Test Coverage]: http://img.shields.io/coveralls/IcecaveStudios/isolator/develop.svg
-[SemVer]: http://img.shields.io/:semver-2.3.0-brightgreen.svg
+[Build Status]: http://img.shields.io/travis/IcecaveStudios/isolator/develop.svg?style=flat-square
+[Test Coverage]: http://img.shields.io/coveralls/IcecaveStudios/isolator/develop.svg?style=flat-square
+[SemVer]: http://img.shields.io/:semver-3.0.0-brightgreen.svg?style=flat-square
diff --git a/benchmark/benchmark.php b/benchmark/benchmark.php
new file mode 100755
index 0000000..a168330
--- /dev/null
+++ b/benchmark/benchmark.php
@@ -0,0 +1,87 @@
+#!/usr/bin/env php
+<?php
+require __DIR__ . '/../vendor/autoload.php';
+
+define('ITERATIONS', 20000);
+
+$isolator = Icecave\Isolator\Isolator::get();
+
+class TestClass
+{
+    public function __construct($param = null)
+    {
+    }
+}
+
+function runBenchmark($name, callable $work)
+{
+    printf('-- %s --' . PHP_EOL, $name);
+
+    $total = 0;
+
+    ob_start();
+
+    for ($i = 0; $i < ITERATIONS; ++$i) {
+        $start = microtime(true);
+        $work();
+        $end = microtime(true);
+        $total += $end - $start;
+    }
+
+    ob_end_clean();
+
+    printf('Iterations:   %d' . PHP_EOL, ITERATIONS);
+    printf('Elapsed Time: %.15f' . PHP_EOL, $total);
+    printf('Average Time: %.15f' . PHP_EOL, $total / ITERATIONS);
+    printf(PHP_EOL);
+}
+
+runBenchmark(
+    'fixed arguments',
+    function () use ($isolator) {
+        $isolator->strlen('foo');
+    }
+);
+
+runBenchmark(
+    'variable arguments',
+    function () use ($isolator) {
+        $isolator->sprintf('%d %d %d %d %d', 1, 2, 3, 4, 5);
+    }
+);
+
+runBenchmark(
+    'reference parameter',
+    function () use ($isolator) {
+        $matches = array();
+        $isolator->preg_match('/./', 'a', $matches);
+    }
+);
+
+runBenchmark(
+    'echo',
+    function () use ($isolator) {
+        $isolator->echo('.');
+    }
+);
+
+runBenchmark(
+    'new',
+    function () use ($isolator) {
+        $isolator->new('TestClass');
+    }
+);
+
+runBenchmark(
+    'new with arguments',
+    function () use ($isolator) {
+        $isolator->new('TestClass', 'arg');
+    }
+);
+
+runBenchmark(
+    'eval',
+    function () use ($isolator) {
+        $isolator->eval('return 1;');
+    }
+);
diff --git a/composer.json b/composer.json
index 5834fd2..e101cbc 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,15 @@
 {
     "name": "icecave/isolator",
     "description": "Dependency injection for global functions.",
-    "keywords": ["test", "phpunit", "phake", "unit", "mock", "fake"],
+    "keywords": [
+        "test",
+        "phpunit",
+        "unit",
+        "mock",
+        "fake",
+        "double",
+        "stub"
+    ],
     "homepage": "https://github.com/IcecaveStudios/isolator",
     "license": "MIT",
     "authors": [
@@ -17,12 +25,17 @@
     "require-dev": {
         "icecave/archer": "~1"
     },
-    "suggest": {
-        "eloquent/asplode": "Drop-in exception-based error handling."
-    },
     "autoload": {
         "psr-4": {
             "Icecave\\Isolator\\": "src"
+        },
+        "files": [
+            "src/register-autoloader.php"
+        ]
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-develop": "3.0.x-dev"
         }
     }
 }
diff --git a/composer.lock b/composer.lock
index f91e8c3..38d1d4b 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "cd3bd98a401c759263120c414cdb77c5",
+    "hash": "709e2c626a4055d53c6114c7e869b2a1",
     "packages": [],
     "packages-dev": [
         {
@@ -160,16 +160,16 @@
         },
         {
             "name": "icecave/archer",
-            "version": "1.2.0",
+            "version": "1.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/IcecaveStudios/archer.git",
-                "reference": "49e90d8c0d0a63e537b26d90591367093ebf45be"
+                "reference": "5b1b4748d0fd6a8f977486d15d10e52e68349379"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/IcecaveStudios/archer/zipball/49e90d8c0d0a63e537b26d90591367093ebf45be",
-                "reference": "49e90d8c0d0a63e537b26d90591367093ebf45be",
+                "url": "https://api.github.com/repos/IcecaveStudios/archer/zipball/5b1b4748d0fd6a8f977486d15d10e52e68349379",
+                "reference": "5b1b4748d0fd6a8f977486d15d10e52e68349379",
                 "shasum": ""
             },
             "require": {
@@ -182,6 +182,7 @@
             },
             "require-dev": {
                 "eloquent/liberator": "~1",
+                "phpunit/phpunit": "~4",
                 "symfony/event-dispatcher": "~2.1"
             },
             "suggest": {
@@ -192,6 +193,11 @@
                 "bin/woodhouse"
             ],
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-develop": "1.3.x-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
                     "Icecave\\Archer\\": "src"
@@ -228,7 +234,7 @@
                 "testing",
                 "unit"
             ],
-            "time": "2014-06-23 00:33:17"
+            "time": "2014-09-18 03:05:28"
         },
         {
             "name": "nikic/php-parser",
@@ -536,17 +542,17 @@
         },
         {
             "name": "symfony/config",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Config",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Config.git",
-                "reference": "8d044668c7ccb4ade684e368d910e3aadcff6f6c"
+                "reference": "0316364bfebc8b080077c731a99f189341476bd7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Config/zipball/8d044668c7ccb4ade684e368d910e3aadcff6f6c",
-                "reference": "8d044668c7ccb4ade684e368d910e3aadcff6f6c",
+                "url": "https://api.github.com/repos/symfony/Config/zipball/0316364bfebc8b080077c731a99f189341476bd7",
+                "reference": "0316364bfebc8b080077c731a99f189341476bd7",
                 "shasum": ""
             },
             "require": {
@@ -580,21 +586,21 @@
             ],
             "description": "Symfony Config Component",
             "homepage": "http://symfony.com",
-            "time": "2014-08-05 09:00:40"
+            "time": "2014-09-23 05:25:11"
         },
         {
             "name": "symfony/console",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Console",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Console.git",
-                "reference": "cd2d1e4bac2206b337326b0140ff475fe9ad5f63"
+                "reference": "ca053eaa031c93afb68a71e4eb1f4168dfd4a661"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Console/zipball/cd2d1e4bac2206b337326b0140ff475fe9ad5f63",
-                "reference": "cd2d1e4bac2206b337326b0140ff475fe9ad5f63",
+                "url": "https://api.github.com/repos/symfony/Console/zipball/ca053eaa031c93afb68a71e4eb1f4168dfd4a661",
+                "reference": "ca053eaa031c93afb68a71e4eb1f4168dfd4a661",
                 "shasum": ""
             },
             "require": {
@@ -635,21 +641,21 @@
             ],
             "description": "Symfony Console Component",
             "homepage": "http://symfony.com",
-            "time": "2014-08-05 09:00:40"
+            "time": "2014-09-25 09:53:56"
         },
         {
             "name": "symfony/event-dispatcher",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/EventDispatcher",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/EventDispatcher.git",
-                "reference": "8faf5cc7e80fde74a650a36e60d32ce3c3e0457b"
+                "reference": "f6281337bf5f985f585d1db6a83adb05ce531f46"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/EventDispatcher/zipball/8faf5cc7e80fde74a650a36e60d32ce3c3e0457b",
-                "reference": "8faf5cc7e80fde74a650a36e60d32ce3c3e0457b",
+                "url": "https://api.github.com/repos/symfony/EventDispatcher/zipball/f6281337bf5f985f585d1db6a83adb05ce531f46",
+                "reference": "f6281337bf5f985f585d1db6a83adb05ce531f46",
                 "shasum": ""
             },
             "require": {
@@ -658,7 +664,7 @@
             "require-dev": {
                 "psr/log": "~1.0",
                 "symfony/config": "~2.0",
-                "symfony/dependency-injection": "~2.0",
+                "symfony/dependency-injection": "~2.0,<2.6.0",
                 "symfony/stopwatch": "~2.2"
             },
             "suggest": {
@@ -692,21 +698,21 @@
             ],
             "description": "Symfony EventDispatcher Component",
             "homepage": "http://symfony.com",
-            "time": "2014-07-28 13:20:46"
+            "time": "2014-09-28 15:56:11"
         },
         {
             "name": "symfony/filesystem",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Filesystem",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Filesystem.git",
-                "reference": "c1309b0ee195ad264a4314435bdaecdfacb8ae9c"
+                "reference": "4e62fab0060a826561c78b665925b37c870c45f5"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Filesystem/zipball/c1309b0ee195ad264a4314435bdaecdfacb8ae9c",
-                "reference": "c1309b0ee195ad264a4314435bdaecdfacb8ae9c",
+                "url": "https://api.github.com/repos/symfony/Filesystem/zipball/4e62fab0060a826561c78b665925b37c870c45f5",
+                "reference": "4e62fab0060a826561c78b665925b37c870c45f5",
                 "shasum": ""
             },
             "require": {
@@ -739,21 +745,21 @@
             ],
             "description": "Symfony Filesystem Component",
             "homepage": "http://symfony.com",
-            "time": "2014-07-09 09:05:48"
+            "time": "2014-09-22 09:14:18"
         },
         {
             "name": "symfony/finder",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Finder",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Finder.git",
-                "reference": "090fe4eaff414d8f2171c7a4748ea868d530775f"
+                "reference": "d5033742b9a6206ef6d06e813870bca18e9205df"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Finder/zipball/090fe4eaff414d8f2171c7a4748ea868d530775f",
-                "reference": "090fe4eaff414d8f2171c7a4748ea868d530775f",
+                "url": "https://api.github.com/repos/symfony/Finder/zipball/d5033742b9a6206ef6d06e813870bca18e9205df",
+                "reference": "d5033742b9a6206ef6d06e813870bca18e9205df",
                 "shasum": ""
             },
             "require": {
@@ -786,21 +792,21 @@
             ],
             "description": "Symfony Finder Component",
             "homepage": "http://symfony.com",
-            "time": "2014-07-28 13:20:46"
+            "time": "2014-09-27 08:35:39"
         },
         {
             "name": "symfony/process",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Process",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Process.git",
-                "reference": "e0997d2a9a1a763484b34b989900b61322a9b056"
+                "reference": "8a1ec96c4e519cee0fb971ea48a1eb7369dda54b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Process/zipball/e0997d2a9a1a763484b34b989900b61322a9b056",
-                "reference": "e0997d2a9a1a763484b34b989900b61322a9b056",
+                "url": "https://api.github.com/repos/symfony/Process/zipball/8a1ec96c4e519cee0fb971ea48a1eb7369dda54b",
+                "reference": "8a1ec96c4e519cee0fb971ea48a1eb7369dda54b",
                 "shasum": ""
             },
             "require": {
@@ -833,21 +839,21 @@
             ],
             "description": "Symfony Process Component",
             "homepage": "http://symfony.com",
-            "time": "2014-08-05 09:00:40"
+            "time": "2014-09-23 05:25:11"
         },
         {
             "name": "symfony/stopwatch",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Stopwatch",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Stopwatch.git",
-                "reference": "086c8c98c3016f59f5e6e7b15b751c2384b311e5"
+                "reference": "9f8a33a24f2378c0ec5f372a8d50b2d43069c050"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Stopwatch/zipball/086c8c98c3016f59f5e6e7b15b751c2384b311e5",
-                "reference": "086c8c98c3016f59f5e6e7b15b751c2384b311e5",
+                "url": "https://api.github.com/repos/symfony/Stopwatch/zipball/9f8a33a24f2378c0ec5f372a8d50b2d43069c050",
+                "reference": "9f8a33a24f2378c0ec5f372a8d50b2d43069c050",
                 "shasum": ""
             },
             "require": {
@@ -880,21 +886,21 @@
             ],
             "description": "Symfony Stopwatch Component",
             "homepage": "http://symfony.com",
-            "time": "2014-08-06 06:44:37"
+            "time": "2014-09-22 09:14:18"
         },
         {
             "name": "symfony/yaml",
-            "version": "v2.5.3",
+            "version": "v2.5.5",
             "target-dir": "Symfony/Component/Yaml",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/Yaml.git",
-                "reference": "5a75366ae9ca8b4792cd0083e4ca4dff9fe96f1f"
+                "reference": "b1dbc53593b98c2d694ebf383660ac9134d30b96"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/Yaml/zipball/5a75366ae9ca8b4792cd0083e4ca4dff9fe96f1f",
-                "reference": "5a75366ae9ca8b4792cd0083e4ca4dff9fe96f1f",
+                "url": "https://api.github.com/repos/symfony/Yaml/zipball/b1dbc53593b98c2d694ebf383660ac9134d30b96",
+                "reference": "b1dbc53593b98c2d694ebf383660ac9134d30b96",
                 "shasum": ""
             },
             "require": {
@@ -927,7 +933,7 @@
             ],
             "description": "Symfony Yaml Component",
             "homepage": "http://symfony.com",
-            "time": "2014-08-05 09:00:40"
+            "time": "2014-09-22 09:14:18"
         },
         {
             "name": "twig/twig",
@@ -990,6 +996,7 @@
     "aliases": [],
     "minimum-stability": "stable",
     "stability-flags": [],
+    "prefer-stable": false,
     "platform": {
         "php": ">=5.3"
     },
diff --git a/src/Detail/AbstractIsolator.php b/src/Detail/AbstractIsolator.php
new file mode 100644
index 0000000..bba587c
--- /dev/null
+++ b/src/Detail/AbstractIsolator.php
@@ -0,0 +1,103 @@
+<?php
+namespace Icecave\Isolator\Detail;
+
+use Icecave\Isolator\Isolator;
+use ReflectionClass;
+
+/**
+ * @internal
+ */
+abstract class AbstractIsolator
+{
+    /**
+     * Forward a call onto global function.
+     *
+     * Support is also provided for the following function-esque language constructs:
+     *
+     *    - exit
+     *    - die
+     *    - echo
+     *    - include
+     *    - include_once
+     *    - require
+     *    - require_once
+     *    - new
+     *
+     * @param string $name      The name of the global function to call.
+     * @param array  $arguments The arguments to the function.
+     *
+     * @return mixed The result of the function call.
+     */
+    public function __call($name, array $arguments)
+    {
+        switch ($name) {
+            case 'exit':
+            case 'die':
+                // @codeCoverageIgnoreStart
+                exit($arguments[0]);
+                // @codeCoverageIgnoreEnd
+            case 'echo':
+                echo $arguments[0];
+
+                return;
+            case 'eval':
+                return eval($arguments[0]);
+            case 'include':
+                return include $arguments[0];
+            case 'include_once':
+                return include_once $arguments[0];
+            case 'require':
+                return require $arguments[0];
+            case 'require_once':
+                return require_once $arguments[0];
+            case 'new':
+                if (1 === \count($arguments)) {
+                    return new $arguments[0]();
+                }
+
+                $reflector = new ReflectionClass(
+                    \array_shift($arguments)
+                );
+
+                return $reflector->newInstanceArgs($arguments);
+        }
+
+        if ($arguments) {
+            return \call_user_func_array($name, $arguments);
+        }
+
+        return $name();
+    }
+
+    /**
+     * Fetch an isolator instance.
+     *
+     * This convenience method returns the global isolator instance, or $instance if provided.
+     *
+     * @param Isolator|null $isolator An existing isolator instance, if available.
+     *
+     * @return Isolator The global isolator instance, or $isolator if provided.
+     */
+    public static function get(Isolator $isolator = null)
+    {
+        if (null !== $isolator) {
+            return $isolator;
+        } elseif (!self::$instance) {
+            self::$instance = new Isolator();
+        }
+
+        return self::$instance;
+    }
+
+    /**
+     * Set the default isolator instance.
+     *
+     * @param Isolator $isolator The isolator instance.
+     */
+    public static function set(Isolator $isolator = null)
+    {
+        self::$instance = $isolator;
+    }
+
+    private static $instance;
+}
diff --git a/src/Detail/Autoloader.php b/src/Detail/Autoloader.php
new file mode 100644
index 0000000..66a5c2a
--- /dev/null
+++ b/src/Detail/Autoloader.php
@@ -0,0 +1,106 @@
+<?php
+namespace Icecave\Isolator\Detail;
+
+use Icecave\Isolator\PackageInfo;
+
+/**
+ * An arcane magic autoloader that generates code for the isolator class when it
+ * is first loaded.
+ */
+class Autoloader
+{
+    /**
+     * @param string        $path          The path under which to store generated code.
+     * @param CodeGenerator $codeGenerator The code generator used to create isolator classes.
+     */
+    public function __construct($path, CodeGenerator $codeGenerator)
+    {
+        $this->path = $path;
+        $this->codeGenerator = $codeGenerator;
+    }
+
+    /**
+     * Load an isolator class with the given name.
+     *
+     * @param string $className The name to give to the isolator class.
+     */
+    public function load($className)
+    {
+        $functions = get_defined_functions();
+        $functions = $functions['internal'];
+
+        $hash = $this->computeHash($className, $functions);
+
+        $fileName = $this->path . DIRECTORY_SEPARATOR . 'Isolator' . $hash . '.php';
+
+        if (!file_exists($fileName)) {
+            $this->generateIsolatorClass(
+                $fileName,
+                $className,
+                $functions
+            );
+        }
+
+        require_once $fileName;
+    }
+
+    /**
+     * Compute a unique hash used to identify an isolator implementation that
+     * proxies the given functions.
+     *
+     * @param string        $className The name to give to the isolator class.
+     * @param array<string> $functions An array of global function names.
+     *
+     * @return string
+     */
+    public function computeHash($className, array $functions)
+    {
+        $hash = hash_init('sha1');
+
+        hash_update($hash, $className);
+
+        foreach ($functions as $function) {
+            hash_update($hash, $function);
+        }
+
+        // Include the PHP version in the hash in case function signatures
+        // change between versions.
+        hash_update($hash, phpversion());
+
+        // Include the Isolator version in the hash in case code generation
+        // changes between versions.
+        hash_update($hash, PackageInfo::VERSION);
+
+        return hash_final($hash);
+    }
+
+    /**
+     * Generate and store an isolator implementation.
+     *
+     * @param string        $className The name to give to the isolator class.
+     * @param array<string> $functions An array of global function names.
+     */
+    public function generateIsolatorClass(
+        $fileName,
+        $className,
+        array $functions
+    ) {
+        $dirName = dirname($fileName);
+
+        if (!file_exists($dirName)) {
+            mkdir($dirName, 0777, true);
+        }
+
+        $code = $this
+            ->codeGenerator
+            ->generate(
+                $className,
+                $functions
+            );
+
+        file_put_contents($fileName, $code);
+    }
+
+    private $path;
+    private $codeGenerator;
+}
diff --git a/src/Detail/CodeGenerator.php b/src/Detail/CodeGenerator.php
new file mode 100644
index 0000000..72bfef8
--- /dev/null
+++ b/src/Detail/CodeGenerator.php
@@ -0,0 +1,168 @@
+<?php
+namespace Icecave\Isolator\Detail;
+
+use ReflectionFunction;
+
+/**
+ * Generates an isolator that can accommodate calls to functions with reference parameters.
+ *
+ * @internal
+ */
+class CodeGenerator
+{
+    public function __construct($ellipsisExpansion = 10)
+    {
+        $this->ellipsisExpansion = $ellipsisExpansion;
+    }
+
+    /**
+     * Generate an isolator implementation.
+     */
+    public function generate($className, array $functions)
+    {
+        $pos = strrpos($className, '\\');
+
+        if ($pos) {
+            $namespace = substr($className, 0, $pos);
+            $shortName = substr($className, $pos + 1);
+        } else {
+            $namespace = null;
+            $shortName = $className;
+        }
+
+        $code  = '<?php' . PHP_EOL;
+
+        if ($namespace) {
+            $code .= 'namespace ' . $namespace . ';' . PHP_EOL;
+        }
+
+        $code .= PHP_EOL;
+        $code .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $code .= PHP_EOL;
+        $code .= 'class ' . $shortName . ' extends AbstractIsolator' . PHP_EOL;
+        $code .= '{' . PHP_EOL;
+
+        foreach ($functions as $function) {
+            $code .= $this->generateMethod(
+                new ReflectionFunction($function)
+            );
+        }
+
+        $code .= '}' . PHP_EOL;
+
+        return $code;
+    }
+
+    private function generateMethod(ReflectionFunction $reflector)
+    {
+        $name = $reflector->getName();
+
+        list($minArity, $maxArity, $refIndices) = $this->inspectParameters($reflector);
+
+        $signature = $this->generateSignature(
+            $name,
+            $reflector->returnsReference(),
+            $minArity,
+            $maxArity,
+            $refIndices
+        );
+
+        $code  = '    ' . $signature . PHP_EOL;
+        $code .= '    {' . PHP_EOL;
+        $code .= $this->generateSwitch($name, $minArity, $maxArity);
+        $code .= '        return \call_user_func_array(' . var_export($reflector->getName(), true) . ', \func_get_args());' . PHP_EOL;
+        $code .= '    }' . PHP_EOL;
+
+        return $code;
+    }
+
+    private function generateSignature(
+        $name,
+        $returnsReference,
+        $minArity,
+        $maxArity,
+        $refIndices
+    ) {
+        $parameters = array();
+
+        for ($index = 0; $index < $maxArity; ++$index) {
+            $param = '$p' . $index;
+
+            if ($refIndices[$index]) {
+                $param = '&' . $param;
+            }
+
+            if ($index >= $minArity) {
+                $param .= ' = null';
+            }
+
+            $parameters[] = $param;
+        }
+
+        return sprintf(
+            'public function %s%s(%s)',
+            $returnsReference ? '&' : '',
+            str_replace('\\', '_', $name),
+            implode(', ', $parameters)
+        );
+    }
+
+    private function generateSwitch($name, $minArity, $maxArity)
+    {
+        $code = '        switch (\func_num_args()) {' . PHP_EOL;
+
+        for ($arity = $minArity; $arity <= $maxArity; ++$arity) {
+            $code .= sprintf(
+                '            case %d: %s',
+                $arity,
+                $this->generateReturn($name, $arity)
+            );
+        }
+
+        $code .= '        }' . PHP_EOL;
+
+        return $code;
+    }
+
+    private function generateReturn($name, $arity)
+    {
+        $arguments = array();
+        for ($index = 0; $index < $arity; ++$index) {
+            $arguments[] = '$p' . $index;
+        }
+
+        return sprintf(
+            'return \%s(%s);' . PHP_EOL,
+            $name,
+            implode(', ', $arguments)
+        );
+    }
+
+    private function inspectParameters(ReflectionFunction $reflector)
+    {
+        $minArity = 0;
+        $maxArity = 0;
+        $refIndices = array();
+
+        foreach ($reflector->getParameters() as $parameter) {
+            // PHP versions < 5.6 showed a parameter named '...' to indicate
+            // that a function took an arbitrary number of arguments.
+            //
+            // @codeCoverageIgnoreStart
+            if ($parameter->getName() === '...') {
+                break;
+            }
+            // @codeCoverageIgnoreEnd
+
+            $refIndices[$maxArity++] = $parameter->isPassedByReference();
+
+            if (!$parameter->isOptional()) {
+                ++$minArity;
+            }
+        }
+
+        return array($minArity, $maxArity, $refIndices);
+    }
+
+    private $ellipsisExpansion;
+}
diff --git a/src/Generator.php b/src/Generator.php
deleted file mode 100644
index e5867aa..0000000
--- a/src/Generator.php
+++ /dev/null
@@ -1,159 +0,0 @@
-<?php
-namespace Icecave\Isolator;
-
-use ReflectionClass;
-use ReflectionFunction;
-
-/**
- * Generates an isolator that can accommodate calls to functions with reference parameters.
- */
-class Generator
-{
-    public function __construct($ellipsisExpansion = 10, Isolator $isolator = null)
-    {
-        $this->ellipsisExpansion = $ellipsisExpansion;
-        $this->isolator = $isolator ?: new Isolator; // Note, Isolator::getIsolator is not used to avoid recursion.
-    }
-
-    public function generateClass(array $functionReflectors, $className = null, $baseClassName = 'Isolator')
-    {
-        if ($className === null) {
-            $className = 'Isolator' . self::$count++;
-        }
-
-        $code    = 'namespace ' . __NAMESPACE__ . ' {' . PHP_EOL;
-        $code .= 'class ' . $className . ' extends ' . $baseClassName . ' {' . PHP_EOL;
-        $code .= PHP_EOL;
-
-        foreach ($functionReflectors as $reflector) {
-            if ($this->requiresIsolatorProxy($reflector)) {
-                $code .= $this->generateProxyMethod($reflector);
-                $code .= PHP_EOL;
-            }
-        }
-
-        $code .= '} // End class.' . PHP_EOL;
-        $code .= '} // End namespace.' . PHP_EOL;
-
-        $this->isolator->eval($code);
-
-        return new ReflectionClass(__NAMESPACE__ . '\\' . $className);
-    }
-
-    public function requiresIsolatorProxy(ReflectionFunction $reflector)
-    {
-        if ($reflector->isDisabled()) {
-            return false;
-        } elseif ($reflector->returnsReference()) {
-            return true;
-        }
-
-        foreach ($reflector->getParameters() as $parameter) {
-            if ($parameter->isPassedByReference()) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    public function inspect(ReflectionFunction $reflector)
-    {
-        $minArity = 0;
-        $maxArity = 0;
-        $refIndices = array();
-
-        foreach ($reflector->getParameters() as $parameter) {
-            $refIndices[$maxArity++] = $parameter->isPassedByReference();
-
-            if (!$parameter->isOptional()) {
-                ++$minArity;
-            }
-
-            if ($parameter->getName() === '...') {
-                $ref = $parameter->isPassedByReference();
-                for ($count = 1; $count < $this->ellipsisExpansion; ++$count) {
-                    $refIndices[$maxArity++] = $ref;
-                }
-                break;
-            }
-        }
-
-        return array($minArity, $maxArity, $refIndices);
-    }
-
-    public function generateProxyMethod(ReflectionFunction $reflector)
-    {
-        list($minArity, $maxArity, $refIndices) = $this->inspect($reflector);
-        $name = $reflector->getName();
-        $code    = $this->generateSignature($name, $reflector->returnsReference(), $minArity, $maxArity, $refIndices) . ' {' . PHP_EOL;
-        $code .= $this->generateSwitch($name, $minArity, $maxArity);
-        $code .= $this->generateReturn($name, $maxArity);
-        $code .= '} // End function ' . $name . '.' . PHP_EOL;
-        $code .= PHP_EOL;
-
-        return $code;
-    }
-
-    protected function generateSignature($name, $returnsReference, $minArity, $maxArity, $refIndices)
-    {
-        $parameters = array();
-        for ($index = 0; $index < $maxArity; ++$index) {
-            $param = '';
-            if ($refIndices[$index]) {
-                $param .= '&';
-            }
-            $param .= '$_' . $index;
-            if ($index >= $minArity) {
-                $param .= ' = null';
-            }
-            $parameters[] = $param;
-        }
-
-        return sprintf(
-            'public function %s%s(%s)'
-            , $returnsReference ? '&' : ''
-            , str_replace('\\', '_', $name)
-            , implode(', ', $parameters)
-        );
-    }
-
-    protected function generateSwitch($name, $minArity, $maxArity)
-    {
-        if ($minArity === $maxArity) {
-            return '';
-        }
-
-        $code    = 'switch (func_num_args()) {' . PHP_EOL;
-
-        for ($arity = $minArity; $arity < $maxArity; ++$arity) {
-            $code .= sprintf(
-                'case %d: %s'
-                , $arity
-                , $this->generateReturn($name, $arity)
-            );
-        }
-
-        $code .= '} // End switch.' . PHP_EOL;
-
-        return $code;
-    }
-
-    protected function generateReturn($name, $arity)
-    {
-        $arguments = array();
-        for ($index = 0; $index < $arity; ++$index) {
-            $arguments[] = '$_' . $index;
-        }
-
-        return sprintf(
-            'return \%s(%s);' . PHP_EOL
-            , $name
-            , implode(', ', $arguments)
-        );
-    }
-
-    private static $count = 0;
-    protected $ellipsisExpansionDepth;
-    protected $isolator;
-}
diff --git a/src/Isolator.php b/src/Isolator.php
deleted file mode 100644
index dc19364..0000000
--- a/src/Isolator.php
+++ /dev/null
@@ -1,144 +0,0 @@
-<?php
-namespace Icecave\Isolator;
-
-use ReflectionClass;
-use ReflectionFunction;
-
-/**
- * Isolate calls to global PHP functions.
- */
-class Isolator
-{
-    /**
-     * Forward a call onto global function.
-     *
-     * Support is also provided for the following function-esque language constructs:
-     *
-     *    - exit
-     *    - die
-     *    - echo
-     *    - include
-     *    - include_once
-     *    - require
-     *    - require_once
-     *    - new
-     *
-     * @param string $name      The name of the global function to call.
-     * @param array  $arguments The arguments to the function.
-     *
-     * @return mixed The result of the function call.
-     */
-    public function __call($name, array $arguments)
-    {
-        switch ($name) {
-            case 'exit':
-            case 'die':
-                // @codeCoverageIgnoreStart
-                exit(current($arguments));
-                // @codeCoverageIgnoreEnd
-            case 'echo':
-                echo current($arguments);
-
-                return;
-            case 'eval':
-                return eval(current($arguments));
-            case 'include':
-                return include current($arguments);
-            case 'include_once':
-                return include_once current($arguments);
-            case 'require':
-                return require current($arguments);
-            case 'require_once':
-                return require_once current($arguments);
-            case 'new':
-                $reflector = new ReflectionClass(
-                    array_shift($arguments)
-                );
-
-                return $reflector->newInstanceArgs($arguments);
-        }
-
-        return call_user_func_array($name, $arguments);
-    }
-
-    /**
-     * Fetch an isolator instance.
-     *
-     * This convenience method returns the global isolator instance, or $instance if provided.
-     *
-     * @param Isolator|null $instance An existing isolator instance, if available.
-     *
-     * @return Isolator The global isolator instance, or $instance if provided.
-     */
-    public static function get(Isolator $instance = null)
-    {
-        if ($instance) {
-            return $instance;
-        }
-
-        return static::getIsolator();
-    }
-
-    /**
-     * Fetch the isolator class name.
-     *
-     * @return string The concrete class name for the global isolator instance.
-     */
-    public static function className()
-    {
-        return get_class(static::get());
-    }
-
-    /**
-     * Fetch the default isolator instance, constructing it if necessary.
-     *
-     * @param boolean        $handleReferences Indicates whether or not the isolator should account for functions with reference parameters and return types.
-     * @param Generator|null $generator        The Generator instance to use to construct the concreate isolator class, or null to use the default.
-     * @param Isolator|null  $isolator         The isolator used to access the global list of functions, or null to use the default.
-     */
-    public static function getIsolator($handleReferences = true, Generator $generator = null, Isolator $isolator = null)
-    {
-        // Global instance already initialized ...
-        if (self::$instance !== null) {
-            return self::$instance;
-        }
-
-        // No need to handle references, rely on default Isolator::__call() method ...
-        if (!$handleReferences) {
-            return self::$instance = new self;
-        }
-
-        // Construct an isolator generator to create the concreate isolator class ...
-        if ($generator === null) {
-            $generator = new Generator;
-        }
-
-        // Get a basic isolator to use for reflection ...
-        if ($isolator === null) {
-            $isolator = new self;
-        }
-
-        // Create reflectors for each of the globally defined functions ...
-        $functionReflectors = array();
-        foreach ($isolator->get_defined_functions() as $functions) {
-            foreach ($functions as $name) {
-                $functionReflectors[] = new ReflectionFunction($name);
-            }
-        }
-
-        // Generate the concrete isolator class and install it as the global instance ...
-        $classReflector = $generator->generateClass($functionReflectors);
-
-        return self::$instance = $classReflector->newInstance();
-    }
-
-    /**
-     * Reset the default isolator instance.
-     */
-    public static function resetIsolator()
-    {
-        self::$instance = null;
-    }
-
-    private static $instance;
-}
diff --git a/src/IsolatorTrait.php b/src/IsolatorTrait.php
index fc0b196..2bc4178 100644
--- a/src/IsolatorTrait.php
+++ b/src/IsolatorTrait.php
@@ -13,7 +13,11 @@ trait IsolatorTrait
      */
     public function isolator()
     {
-        return Isolator::get($this->isolator);
+        if ($this->isolator) {
+            return $this->isolator;
+        }
+
+        return Isolator::get();
     }
 
     /**
diff --git a/src/PackageInfo.php b/src/PackageInfo.php
index 30f10ed..45ce146 100644
--- a/src/PackageInfo.php
+++ b/src/PackageInfo.php
@@ -4,5 +4,5 @@
 class PackageInfo
 {
     const NAME = 'Isolator';
-    const VERSION = '2.3.0';
+    const VERSION = '3.0.0';
 }
diff --git a/src/register-autoloader.php b/src/register-autoloader.php
new file mode 100644
index 0000000..d17ec03
--- /dev/null
+++ b/src/register-autoloader.php
@@ -0,0 +1,19 @@
+<?php
+
+spl_autoload_register(
+    /**
+     * @codeCoverageIgnore
+     */
+    function ($className) {
+        if ($className !== 'Icecave\Isolator\Isolator') {
+            return;
+        }
+
+        $autoloader = new Icecave\Isolator\Detail\Autoloader(
+            sys_get_temp_dir() . DIRECTORY_SEPARATOR . 'isolator',
+            new Icecave\Isolator\Detail\CodeGenerator()
+        );
+
+        $autoloader->load($className);
+    }
+);
diff --git a/test/src/function.php b/test/src/function.php
new file mode 100644
index 0000000..76a1684
--- /dev/null
+++ b/test/src/function.php
@@ -0,0 +1,7 @@
+<?php
+
+if (class_exists('Icecave\Isolator\Isolator', false)) {
+    function icecaveIsolatorPostGeneration($value = null) {
+        return $value;
+    }
+}
diff --git a/test/suite/Detail/AutoloaderTest.php b/test/suite/Detail/AutoloaderTest.php
new file mode 100644
index 0000000..5733520
--- /dev/null
+++ b/test/suite/Detail/AutoloaderTest.php
@@ -0,0 +1,45 @@
+<?php
+namespace Icecave\Isolator\Detail;
+
+use Phake;
+use PHPUnit_Framework_TestCase;
+
+class AutoloaderTest extends PHPUnit_Framework_TestCase
+{
+    public function setUp()
+    {
+        $this->path = tempnam(sys_get_temp_dir(), 'isolator-');
+        $this->codeGenerator = Phake::mock(__NAMESPACE__ . '\CodeGenerator');
+
+        $this->autoloader = new Autoloader(
+            $this->path,
+            $this->codeGenerator
+        );
+
+        unlink($this->path);
+
+        Phake::when($this->codeGenerator)
+            ->generate(Phake::anyParameters())
+            ->thenReturn('<?php echo "Included!";');
+    }
+
+    public function testLoad()
+    {
+        $this->expectOutputString('Included!');
+
+        $this->autoloader->load('Foo');
+
+        $functions = get_defined_functions();
+
+        Phake::verify($this->codeGenerator)->generate(
+            'Foo',
+            $functions['internal']
+        );
+
+        // Additional load should not produce additional output ...
+        $this->autoloader->load('Foo');
+
+        Phake::verify($this->codeGenerator, Phake::times(1))->generate(Phake::anyParameters());
+    }
+
+}
diff --git a/test/suite/Detail/CodeGeneratorTest.php b/test/suite/Detail/CodeGeneratorTest.php
new file mode 100644
index 0000000..ea80565
--- /dev/null
+++ b/test/suite/Detail/CodeGeneratorTest.php
@@ -0,0 +1,140 @@
+<?php
+namespace Icecave\Isolator\Detail;
+
+use PHPUnit_Framework_TestCase;
+
+class CodeGeneratorTest extends PHPUnit_Framework_TestCase
+{
+    public function setUp()
+    {
+        $this->generator = new CodeGenerator();
+    }
+
+    public function testGenerateClass()
+    {
+        $code = $this->generator->generate(
+            'Foo',
+            array()
+        );
+
+        $expectedCode  = '<?php' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'class Foo extends AbstractIsolator' . PHP_EOL;
+        $expectedCode .= '{' . PHP_EOL;
+        $expectedCode .= '}' . PHP_EOL;
+
+        $this->assertSame(
+            $expectedCode,
+            $code
+        );
+    }
+
+    public function testGenerateClassInNamespace()
+    {
+        $code = $this->generator->generate(
+            'Foo\Bar\Spam',
+            array()
+        );
+
+        $expectedCode  = '<?php' . PHP_EOL;
+        $expectedCode .= 'namespace Foo\Bar;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'class Spam extends AbstractIsolator' . PHP_EOL;
+        $expectedCode .= '{' . PHP_EOL;
+        $expectedCode .= '}' . PHP_EOL;
+
+        $this->assertSame(
+            $expectedCode,
+            $code
+        );
+    }
+
+    public function testGenerateMethod()
+    {
+        $code = $this->generator->generate(
+            'Foo',
+            array('strlen')
+        );
+
+        $expectedCode  = '<?php' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'class Foo extends AbstractIsolator' . PHP_EOL;
+        $expectedCode .= '{' . PHP_EOL;
+        $expectedCode .= '    public function strlen($p0)' . PHP_EOL;
+        $expectedCode .= '    {' . PHP_EOL;
+        $expectedCode .= '        switch (\func_num_args()) {' . PHP_EOL;
+        $expectedCode .= '            case 1: return \strlen($p0);' . PHP_EOL;
+        $expectedCode .= '        }' . PHP_EOL;
+        $expectedCode .= '        return \call_user_func_array(\'strlen\', \func_get_args());' . PHP_EOL;
+        $expectedCode .= '    }' . PHP_EOL;
+        $expectedCode .= '}' . PHP_EOL;
+
+        $this->assertSame(
+            $expectedCode,
+            $code
+        );
+    }
+
+    public function testGenerateMethodWithReferenceParameter()
+    {
+        $code = $this->generator->generate(
+            'Foo',
+            array('ereg')
+        );
+
+        $expectedCode  = '<?php' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'class Foo extends AbstractIsolator' . PHP_EOL;
+        $expectedCode .= '{' . PHP_EOL;
+        $expectedCode .= '    public function ereg($p0, $p1, &$p2 = null)' . PHP_EOL;
+        $expectedCode .= '    {' . PHP_EOL;
+        $expectedCode .= '        switch (\func_num_args()) {' . PHP_EOL;
+        $expectedCode .= '            case 2: return \ereg($p0, $p1);' . PHP_EOL;
+        $expectedCode .= '            case 3: return \ereg($p0, $p1, $p2);' . PHP_EOL;
+        $expectedCode .= '        }' . PHP_EOL;
+        $expectedCode .= '        return \call_user_func_array(\'ereg\', \func_get_args());' . PHP_EOL;
+        $expectedCode .= '    }' . PHP_EOL;
+        $expectedCode .= '}' . PHP_EOL;
+
+        $this->assertSame(
+            $expectedCode,
+            $code
+        );
+    }
+
+    public function testGenerateMethodWithVarArgs()
+    {
+        $code = $this->generator->generate(
+            'Foo',
+            array('sprintf')
+        );
+
+        $expectedCode  = '<?php' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'use Icecave\Isolator\Detail\AbstractIsolator;' . PHP_EOL;
+        $expectedCode .= PHP_EOL;
+        $expectedCode .= 'class Foo extends AbstractIsolator' . PHP_EOL;
+        $expectedCode .= '{' . PHP_EOL;
+        $expectedCode .= '    public function sprintf($p0, $p1)' . PHP_EOL;
+        $expectedCode .= '    {' . PHP_EOL;
+        $expectedCode .= '        switch (\func_num_args()) {' . PHP_EOL;
+        $expectedCode .= '            case 2: return \sprintf($p0, $p1);' . PHP_EOL;
+        $expectedCode .= '        }' . PHP_EOL;
+        $expectedCode .= '        return \call_user_func_array(\'sprintf\', \func_get_args());' . PHP_EOL;
+        $expectedCode .= '    }' . PHP_EOL;
+        $expectedCode .= '}' . PHP_EOL;
+
+        $this->assertSame(
+            $expectedCode,
+            $code
+        );
+    }
+}
diff --git a/test/suite/GeneratorTest.php b/test/suite/GeneratorTest.php
deleted file mode 100644
index 5460eca..0000000
--- a/test/suite/GeneratorTest.php
+++ /dev/null
@@ -1,390 +0,0 @@
-<?php
-namespace Icecave\Isolator;
-
-use ReflectionFunction;
-use PHPUnit_Framework_TestCase;
-use Phake;
-
-class GeneratorTest extends PHPUnit_Framework_TestCase
-{
-    public function setUp()
-    {
-        $this->isolator = Phake::mock('Icecave\Isolator\Isolator');
-        $this->generator = Phake::partialMock(
-            'Icecave\Isolator\Generator',
-            5,
-            $this->isolator
-        );
-    }
-
-    public function testCallWithReference()
-    {
-        $isolator = Isolator::get();
-
-        $matches = array();
-
-        $isolator->preg_match('/.*/', 'foo', $matches);
-
-        $this->assertSame(array('foo'), $matches);
-    }
-
-    public function testGenerateClass()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $reflectors = array($reflector);
-
-        Phake::when($this->generator)
-            ->requiresIsolatorProxy(Phake::anyParameters())
-            ->thenReturn(true);
-
-        Phake::when($this->generator)
-            ->generateProxyMethod(Phake::anyParameters())
-            ->thenReturn('/* method goes here */');
-
-        $this->setExpectedException('ReflectionException', 'Class Icecave\Isolator\TestIsolatorClass does not exist');
-        try {
-            $this->generator->generateClass($reflectors, 'TestIsolatorClass');
-        } catch (ReflectionException $e) {
-            $expectedCode  = 'namespace Icecave\Isolator {' . PHP_EOL;
-            $expectedCode .= 'class TestIsolatorClass extends Isolator {' . PHP_EOL;
-            $expectedCode .= PHP_EOL;
-            $expectedCode .= '/* method goes here */' . PHP_EOL;
-            $expectedCode .= '} // End class.' . PHP_EOL;
-            $expectedCode .= '} // End namespace.' . PHP_EOL;
-
-            Phake::inOrder(
-                Phake::verify($this->generator)->requiresIsolatorProxy($reflector),
-                Phake::verify($this->generator)->generateProxyMethod($reflector),
-                Phake::verify($this->isolator)->eval($expectedCode)
-            );
-            throw $e;
-        }
-    }
-
-    public function testInspect()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(true);
-
-        Phake::when($parameter1)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isOptional()
-            ->thenReturn(true);
-
-        $expected = array(
-            1,
-            2,
-            array(false, true),
-        );
-
-        $this->assertSame($expected, $this->generator->inspect($reflector));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter1)->isOptional(),
-            Phake::verify($parameter1)->getName(),
-            Phake::verify($parameter2)->isPassedByReference(),
-            Phake::verify($parameter2)->isOptional(),
-            Phake::verify($parameter2)->getName()
-        );
-    }
-
-    public function testInspectEllipsis()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter1)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->getName()
-            ->thenReturn('...');
-
-        $expected = array(
-            2,
-            6,
-            array(
-                false,
-                false,
-                false,
-                false,
-                false,
-                false,
-            ),
-        );
-
-        $this->assertSame($expected, $this->generator->inspect($reflector));
-
-        $parameter2Verifier = Phake::verify($parameter2, Phake::times(2));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter1)->isOptional(),
-            Phake::verify($parameter1)->getName(),
-            $parameter2Verifier->isPassedByReference(),
-            Phake::verify($parameter2)->isOptional(),
-            Phake::verify($parameter2)->getName(),
-            $parameter2Verifier->isPassedByReference()
-        );
-    }
-
-    public function testInspectEllipsisOptional()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter1)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isOptional()
-            ->thenReturn(true);
-
-        Phake::when($parameter2)
-            ->getName()
-            ->thenReturn('...');
-
-        $expected = array(
-            1,
-            6,
-            array(
-                false,
-                false,
-                false,
-                false,
-                false,
-                false,
-            ),
-        );
-
-        $this->assertSame($expected, $this->generator->inspect($reflector));
-
-        $parameter2Verifier = Phake::verify($parameter2, Phake::times(2));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter1)->isOptional(),
-            Phake::verify($parameter1)->getName(),
-            $parameter2Verifier->isPassedByReference(),
-            Phake::verify($parameter2)->isOptional(),
-            Phake::verify($parameter2)->getName(),
-            $parameter2Verifier->isPassedByReference()
-        );
-    }
-
-    public function testInspectEllipsisReference()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(true);
-
-        Phake::when($parameter1)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isOptional()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->getName()
-            ->thenReturn('...');
-
-        $expected = array(
-            2,
-            6,
-            array(
-                false,
-                true,
-                true,
-                true,
-                true,
-                true,
-            ),
-        );
-
-        $this->assertSame($expected, $this->generator->inspect($reflector));
-
-        $parameter2Verifier = Phake::verify($parameter2, Phake::times(2));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter1)->isOptional(),
-            Phake::verify($parameter1)->getName(),
-            $parameter2Verifier->isPassedByReference(),
-            Phake::verify($parameter2)->isOptional(),
-            Phake::verify($parameter2)->getName(),
-            $parameter2Verifier->isPassedByReference()
-        );
-    }
-
-    public function testRequiresIsolatorProxyDisabled()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        Phake::when($reflector)
-            ->isDisabled()
-            ->thenReturn(true);
-
-        $this->assertFalse($this->generator->requiresIsolatorProxy($reflector));
-
-        Phake::verify($reflector)->isDisabled();
-    }
-
-    public function testRequiresIsolatorProxyReturnsReference()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        Phake::when($reflector)
-            ->isDisabled()
-            ->thenReturn(false);
-
-        Phake::when($reflector)
-            ->returnsReference()
-            ->thenReturn(true);
-
-        $this->assertTrue($this->generator->requiresIsolatorProxy($reflector));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->isDisabled(),
-            Phake::verify($reflector)->returnsReference()
-        );
-    }
-
-    public function testRequiresIsolatorProxyReferenceParameter()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->isDisabled()
-            ->thenReturn(false);
-
-        Phake::when($reflector)
-            ->returnsReference()
-            ->thenReturn(false);
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(true);
-
-        $this->assertTrue($this->generator->requiresIsolatorProxy($reflector));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->isDisabled(),
-            Phake::verify($reflector)->returnsReference(),
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter2)->isPassedByReference()
-        );
-    }
-
-    public function testRequiresIsolatorProxyNoReferenceParameters()
-    {
-        $reflector = Phake::mock('ReflectionFunction');
-        $parameter1 = Phake::mock('ReflectionParameter');
-        $parameter2 = Phake::mock('ReflectionParameter');
-
-        Phake::when($reflector)
-            ->isDisabled()
-            ->thenReturn(false);
-
-        Phake::when($reflector)
-            ->returnsReference()
-            ->thenReturn(false);
-
-        Phake::when($reflector)
-            ->getParameters()
-            ->thenReturn(array($parameter1, $parameter2));
-
-        Phake::when($parameter1)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        Phake::when($parameter2)
-            ->isPassedByReference()
-            ->thenReturn(false);
-
-        $this->assertFalse($this->generator->requiresIsolatorProxy($reflector));
-
-        Phake::inOrder(
-            Phake::verify($reflector)->isDisabled(),
-            Phake::verify($reflector)->returnsReference(),
-            Phake::verify($reflector)->getParameters(),
-            Phake::verify($parameter1)->isPassedByReference(),
-            Phake::verify($parameter2)->isPassedByReference()
-        );
-    }
-}
diff --git a/test/suite/IsolatorTest.php b/test/suite/IsolatorTest.php
index b27c2a8..fde13c1 100644
--- a/test/suite/IsolatorTest.php
+++ b/test/suite/IsolatorTest.php
@@ -2,174 +2,197 @@
 namespace Icecave\Isolator;
 
 use DateTime;
-use Phake;
 use PHPUnit_Framework_TestCase;
-use ReflectionClass;
-use ReflectionFunction;
 use SplObjectStorage;
 
+/**
+ * @covers Icecave\Isolator\Isolator
+ * @covers Icecave\Isolator\Detail\AbstractIsolator
+ */
 class IsolatorTest extends PHPUnit_Framework_TestCase
 {
+    public function setUp()
+    {
+        $this->isolator = new Isolator();
+    }
+
     public function tearDown()
     {
-        parent::tearDown();
-        Isolator::resetIsolator();
+        Isolator::set(null);
     }
 
     public function testCall()
     {
-        $isolator = new Isolator;
-        $this->assertSame(3, $isolator->strlen('foo'));
+        $this->assertSame(
+            3,
+            $this->isolator->strlen('foo')
+        );
+    }
+
+    public function testCallWithReference()
+    {
+        $matches = array();
+
+        $this->isolator->preg_match(
+            '/.*/',
+            'foo',
+            $matches
+        );
+
+        $this->assertSame(
+            array('foo'),
+            $matches
+        );
+    }
+
+    public function testCallWithVarArgs()
+    {
+        $this->assertSame(
+            'a b c',
+            $this->isolator->sprintf(
+                '%s %s %s',
+                'a',
+                'b',
+                'c'
+            )
+        );
+    }
+
+    public function testCallFunctionDefinedAfterIsolatorCreated()
+    {
+        if (function_exists('icecaveIsolatorPostGeneration')) {
+            $this->markTestSkipped('This test can only be executed once.');
+        }
+
+        require __DIR__ . '/../src/function.php';
+
+        $this->assertNull(
+            $this->isolator->icecaveIsolatorPostGeneration()
+        );
+
+        $this->assertSame(
+            $this->isolator->icecaveIsolatorPostGeneration(123),
+            123
+        );
     }
 
     public function testEcho()
     {
-        $isolator = new Isolator;
         $this->expectOutputString('Echo works!');
-        $isolator->echo('Echo works!');
+
+        $this->isolator->echo('Echo works!');
     }
 
     public function testEval()
     {
-        $isolator = new Isolator;
-        $this->assertSame(3, $isolator->eval('return strlen("foo");'));
+        $this->assertSame(
+            3,
+            $this->isolator->eval('return strlen("foo");')
+        );
     }
 
     public function testInclude()
     {
-        $isolator = new Isolator;
-        $this->assertFalse(class_exists('Icecave\Isolator\ClassA', false));
+        $this->assertFalse(
+            class_exists('Icecave\Isolator\ClassA', false)
+        );
 
         $this->assertSame(
             'returnValueA',
-            $isolator->include(__DIR__ . '/../src/ClassA.php')
+            $this->isolator->include(__DIR__ . '/../src/ClassA.php')
+        );
+
+        $this->assertTrue(
+            class_exists('Icecave\Isolator\ClassA', false)
         );
-        $this->assertTrue(class_exists('Icecave\Isolator\ClassA', false));
     }
 
     public function testIncludeOnce()
     {
-        $isolator = new Isolator;
-        $this->assertFalse(class_exists('Icecave\Isolator\ClassB', false));
+        $this->assertFalse(
+            class_exists('Icecave\Isolator\ClassB', false)
+        );
 
         $this->assertSame(
             'returnValueB',
-            $isolator->include_once(__DIR__ . '/../src/ClassB.php')
+            $this->isolator->include_once(__DIR__ . '/../src/ClassB.php')
+        );
+
+        $this->assertTrue(
+            class_exists('Icecave\Isolator\ClassB', false)
         );
-        $this->assertTrue(class_exists('Icecave\Isolator\ClassB', false));
     }
 
     public function testRequire()
     {
-        $isolator = new Isolator;
-        $this->assertFalse(class_exists('Icecave\Isolator\ClassC', false));
+        $this->assertFalse(
+            class_exists('Icecave\Isolator\ClassC', false)
+        );
 
         $this->assertSame(
             'returnValueC',
-            $isolator->require(__DIR__ . '/../src/ClassC.php')
+            $this->isolator->require(__DIR__ . '/../src/ClassC.php')
+        );
+
+        $this->assertTrue(
+            class_exists('Icecave\Isolator\ClassC', false)
         );
-        $this->assertTrue(class_exists('Icecave\Isolator\ClassC', false));
     }
 
     public function testRequireOnce()
     {
-        $isolator = new Isolator;
-        $this->assertFalse(class_exists('Icecave\Isolator\ClassD', false));
+        $this->assertFalse(
+            class_exists('Icecave\Isolator\ClassD', false)
+        );
 
         $this->assertSame(
             'returnValueD',
-            $isolator->require_once(__DIR__ . '/../src/ClassD.php')
+            $this->isolator->require_once(__DIR__ . '/../src/ClassD.php')
+        );
+
+        $this->assertTrue(
+            class_exists('Icecave\Isolator\ClassD', false)
         );
-        $this->assertTrue(class_exists('Icecave\Isolator\ClassD', false));
     }
 
     public function testNew()
     {
-        $isolator = new Isolator;
-
         $this->assertEquals(
-            new SplObjectStorage,
-            $isolator->new('SplObjectStorage')
+            new SplObjectStorage(),
+            $this->isolator->new('SplObjectStorage')
         );
     }
 
     public function testNewWithConstructorArguments()
     {
-        $isolator = new Isolator;
-
         $this->assertEquals(
             new DateTime('2014-01-01 01:02:03 GMT'),
-            $isolator->new('DateTime', '2014-01-01 01:02:03 GMT')
+            $this->isolator->new('DateTime', '2014-01-01 01:02:03 GMT')
         );
     }
 
     public function testGet()
     {
-        $isolator = new Isolator;
-        $this->assertSame($isolator, Isolator::get($isolator));
-        $this->assertInstanceOf('Icecave\Isolator\Isolator', Isolator::get(null));
-    }
-
-    public function testGetIsolator()
-    {
-        $isolator = Isolator::getIsolator();
-        $this->assertInstanceOf('Icecave\Isolator\Isolator', $isolator);
-        $this->assertSame($isolator, Isolator::getIsolator());
-    }
-
-    public function testGetIsolatorNoReferences()
-    {
-        $isolator = Isolator::getIsolator(false);
-        $this->assertSame('Icecave\Isolator\Isolator', get_class($isolator));
-    }
+        $this->assertSame(
+            $this->isolator,
+            Isolator::get($this->isolator)
+        );
 
-    public function testGetIsolatorExistingInstance()
-    {
-        $isolator = Isolator::getIsolator(false);
-        $this->assertInstanceOf('Icecave\Isolator\Isolator', $isolator);
-        $this->assertSame($isolator, Isolator::getIsolator(false));
-    }
+        $globalIsolator = Isolator::get();
 
-    public function testGetIsolatorNewInstance()
-    {
-        $generator = Phake::mock('Icecave\Isolator\Generator');
-        Phake::when($generator)
-            ->generateClass(Phake::anyParameters())
-            ->thenReturn(new ReflectionClass('Icecave\Isolator\Isolator'));
-
-        $functions = array(
-            'internal' => array(
-                'strlen'
-            )
+        $this->assertInstanceOf(
+            'Icecave\Isolator\Isolator',
+            $globalIsolator
         );
 
-        $reflectors = array(
-            new ReflectionFunction('strlen')
+        $this->assertNotSame(
+            $this->isolator,
+            $globalIsolator
         );
 
-        $internalIsolator = Phake::mock('Icecave\Isolator\Isolator');
-        Phake::when($internalIsolator)
-            ->get_defined_functions()
-            ->thenReturn($functions);
-
-        $isolator = Isolator::getIsolator(true, $generator, $internalIsolator);
-        $this->assertInstanceOf('Icecave\Isolator\Isolator', $isolator);
-
-        Phake::inOrder(
-            Phake::verify($internalIsolator)->get_defined_functions()
-            , Phake::verify($generator)->generateClass($reflectors)
+        $this->assertSame(
+            $globalIsolator,
+            Isolator::get()
         );
-
-        // Invoking a second time should not produce any additional calls to the generator or isolator ...
-        Phake::verifyNoFurtherInteraction($generator);
-        Phake::verifyNoFurtherInteraction($internalIsolator);
-        $this->assertSame($isolator, Isolator::getIsolator(true, $generator, $isolator));
-    }
-
-    public function testClassName()
-    {
-        $isolator = Isolator::getIsolator();
-
-        $this->assertSame(get_class($isolator), Isolator::className());
     }
 }
diff --git a/test/suite/IsolatorTraitTest.php b/test/suite/IsolatorTraitTest.php
index 81f7bda..183dc91 100644
--- a/test/suite/IsolatorTraitTest.php
+++ b/test/suite/IsolatorTraitTest.php
@@ -12,7 +12,7 @@ class IsolatorTraitTest extends PHPUnit_Framework_TestCase
 {
     public function testIsolator()
     {
-        $object = new TraitUsage;
+        $object = new TraitUsage();
 
         $instance = Isolator::get();