diff --git a/Sources/Time/8-Formatting/FormatTemplates.swift b/Sources/Time/8-Formatting/FormatTemplates.swift
index fe1229e..fbe2373 100644
--- a/Sources/Time/8-Formatting/FormatTemplates.swift
+++ b/Sources/Time/8-Formatting/FormatTemplates.swift
@@ -7,6 +7,8 @@
 
 import Foundation
 
+#warning("TODO: document these")
+
 public struct Template<F>: Format {
     internal let template: String
     internal init(_ template: String) {
diff --git a/Sources/Time/Internals/DateFormatterCache.swift b/Sources/Time/Internals/DateFormatterCache.swift
index 768123d..9994db3 100644
--- a/Sources/Time/Internals/DateFormatterCache.swift
+++ b/Sources/Time/Internals/DateFormatterCache.swift
@@ -39,38 +39,37 @@ private class DateFormatterCache {
     
     static let shared = DateFormatterCache()
     
-    #warning("TODO: better locking primitive?")
-    private let queue = DispatchQueue(label: "DateFormatterCache")
-    
+    private let lock = NSLock()
     private var formatters = Dictionary<DateFormatter.Key, DateFormatter>()
     
     private init() { }
     
-    private func onqueue_nonupdatingFormatter(for key: DateFormatter.Key) -> DateFormatter {
-        if let existing = formatters[key] { return existing }
+    func formatter(for key: DateFormatter.Key) -> DateFormatter {
+        lock.lock()
+        let returnValue: DateFormatter
         
-        let formatter = DateFormatter()
-        formatter.locale = key.region.locale
-        formatter.calendar = key.region.calendar
-        formatter.timeZone = key.region.timeZone
-        switch key.configuration {
-            case .template(let template):
-                formatter.dateFormat = DateFormatter.dateFormat(fromTemplate: template, options: 0, locale: key.region.locale)
-            case .raw(let format):
-                formatter.dateFormat = format
-            case .styles(let date, let time):
-                formatter.dateStyle = date
-                formatter.timeStyle = time
+        if let existing = formatters[key] {
+            returnValue = existing
+        } else {
+            let formatter = DateFormatter()
+            formatter.locale = key.region.locale
+            formatter.calendar = key.region.calendar
+            formatter.timeZone = key.region.timeZone
+            switch key.configuration {
+                case .template(let template):
+                    formatter.dateFormat = DateFormatter.dateFormat(fromTemplate: template, options: 0, locale: key.region.locale)
+                case .raw(let format):
+                    formatter.dateFormat = format
+                case .styles(let date, let time):
+                    formatter.dateStyle = date
+                    formatter.timeStyle = time
+            }
+            formatters[key] = formatter
+            returnValue = formatter
         }
-        formatters[key] = formatter
         
-        return formatter
-    }
-    
-    func formatter(for key: DateFormatter.Key) -> DateFormatter {
-        return queue.sync {
-            return onqueue_nonupdatingFormatter(for: key)
-        }
+        lock.unlock()
+        return returnValue
     }
     
 }
diff --git a/Sources/Time/Internals/SimpleCache.swift b/Sources/Time/Internals/SimpleCache.swift
index 3fc13d9..0e2474f 100644
--- a/Sources/Time/Internals/SimpleCache.swift
+++ b/Sources/Time/Internals/SimpleCache.swift
@@ -34,8 +34,6 @@ extension TimeZone {
 private class SimpleCache<Key: Hashable, T> {
     
     private var storage = Dictionary<Key, T>()
-    
-    #warning("TODO: better synchronization primitive?")
     private let lock = NSLock()
     
     init() { }
diff --git a/Sources/Time/Internals/Snapshot.swift b/Sources/Time/Internals/Snapshot.swift
index 83bb69e..fc4ff28 100644
--- a/Sources/Time/Internals/Snapshot.swift
+++ b/Sources/Time/Internals/Snapshot.swift
@@ -89,8 +89,6 @@ private class Snapshot<T> {
     
     private var _snapshot: T?
     private var observationToken: NSObjectProtocol?
-    
-    #warning("TODO: better synchronization primitive?")
     private let lock = NSLock()
     
     var snapshot: T {