diff --git a/.cargo/config.toml b/.cargo/config.toml
index d9c635df5dc7..4e96bd6b58c0 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -23,3 +23,7 @@ split-debuginfo = "unpacked"
 rustflags = ["--remap-path-prefix", "=clippy_dev"]
 [profile.dev.package.lintcheck]
 rustflags = ["--remap-path-prefix", "=lintcheck"]
+
+# Configure malloc for faster compiling Clippy itself
+[env]
+MALLOC_CONF = "percpu_arena:phycpu,metadata_thp:always,dirty_decay_ms:300,muzzy_decay_ms:300"
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index ba80e122448d..a771cbe14276 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -579,6 +579,10 @@ fn register_categories(store: &mut rustc_lint::LintStore) {
 /// Used in `./src/driver.rs`.
 #[expect(clippy::too_many_lines)]
 pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
+    // Avoid unnecessary reallocations
+    store.late_passes.reserve(320);
+    store.early_passes.reserve(64);
+
     register_categories(store);
 
     for (old_name, new_name) in deprecated_lints::RENAMED {