diff --git a/docs/introspection.md b/docs/introspection.md
index 9e3fe464..f09cff91 100644
--- a/docs/introspection.md
+++ b/docs/introspection.md
@@ -13,3 +13,10 @@
 ```bash
 CI=1 CODSPEED_DEBUG=true pnpm --filter with-typescript-esm bench-tinybench
 ```
+
+## Garbage collection
+
+Memory and simulation modes receive `--expose-gc` through introspection.
+The Benchmark.js plugin collects warmup garbage before starting instrumentation
+for both synchronous and asynchronous benchmarks. This keeps the forced
+collection outside the measured window.
diff --git a/packages/benchmark.js-plugin/src/index.ts b/packages/benchmark.js-plugin/src/index.ts
index fa69a35a..7d93d46d 100644
--- a/packages/benchmark.js-plugin/src/index.ts
+++ b/packages/benchmark.js-plugin/src/index.ts
@@ -207,6 +207,7 @@ async function runBenchmarks({
     } else {
       optimizeFunctionSync(benchPayload);
       await mongoMeasurement.start(uri);
+      global.gc?.();
       wrapWithRootFrameSync(() => {
         InstrumentHooks.startBenchmark();
         benchPayload();