diff --git a/packages/vitest/src/node/pools/forks.ts b/packages/vitest/src/node/pools/forks.ts
index 0f558dd788ba..bfc739cc5503 100644
--- a/packages/vitest/src/node/pools/forks.ts
+++ b/packages/vitest/src/node/pools/forks.ts
@@ -29,7 +29,7 @@ function createChildProcessChannel(project: WorkspaceProject) {
     postMessage: message => emitter.emit(events.response, message),
   }
 
-  const rpc = createBirpc<RunnerRPC, RuntimeRPC>(createMethodsRPC(project), {
+  const rpc = createBirpc<RunnerRPC, RuntimeRPC>(createMethodsRPC(project, { cacheFs: true }), {
     eventNames: ['onCancel'],
     serialize: v8.serialize,
     deserialize: v => v8.deserialize(Buffer.from(v)),
diff --git a/packages/vitest/src/node/pools/rpc.ts b/packages/vitest/src/node/pools/rpc.ts
index 452b3bb3d088..3ce3324bb27e 100644
--- a/packages/vitest/src/node/pools/rpc.ts
+++ b/packages/vitest/src/node/pools/rpc.ts
@@ -8,8 +8,13 @@ import type { WorkspaceProject } from '../workspace'
 const created = new Set()
 const promises = new Map<string, Promise<void>>()
 
-export function createMethodsRPC(project: WorkspaceProject): RuntimeRPC {
+interface MethodsOptions {
+  cacheFs?: boolean
+}
+
+export function createMethodsRPC(project: WorkspaceProject, options: MethodsOptions = {}): RuntimeRPC {
   const ctx = project.ctx
+  const cacheFs = options.cacheFs ?? false
   return {
     snapshotSaved(snapshot) {
       ctx.snapshot.add(snapshot)
@@ -30,7 +35,7 @@ export function createMethodsRPC(project: WorkspaceProject): RuntimeRPC {
     async fetch(id, transformMode) {
       const result = await project.vitenode.fetchResult(id, transformMode)
       const code = result.code
-      if (result.externalize) {
+      if (!cacheFs || result.externalize) {
         return result
       }
       if ('id' in result && typeof result.id === 'string') {
diff --git a/packages/vitest/src/node/pools/vmForks.ts b/packages/vitest/src/node/pools/vmForks.ts
index 636698a2a28c..5c55a3181311 100644
--- a/packages/vitest/src/node/pools/vmForks.ts
+++ b/packages/vitest/src/node/pools/vmForks.ts
@@ -34,20 +34,23 @@ function createChildProcessChannel(project: WorkspaceProject) {
     postMessage: message => emitter.emit(events.response, message),
   }
 
-  const rpc = createBirpc<RunnerRPC, RuntimeRPC>(createMethodsRPC(project), {
-    eventNames: ['onCancel'],
-    serialize: v8.serialize,
-    deserialize: v => v8.deserialize(Buffer.from(v)),
-    post(v) {
-      emitter.emit(events.message, v)
+  const rpc = createBirpc<RunnerRPC, RuntimeRPC>(
+    createMethodsRPC(project, { cacheFs: true }),
+    {
+      eventNames: ['onCancel'],
+      serialize: v8.serialize,
+      deserialize: v => v8.deserialize(Buffer.from(v)),
+      post(v) {
+        emitter.emit(events.message, v)
+      },
+      on(fn) {
+        emitter.on(events.response, fn)
+      },
+      onTimeoutError(functionName) {
+        throw new Error(`[vitest-pool]: Timeout calling "${functionName}"`)
+      },
     },
-    on(fn) {
-      emitter.on(events.response, fn)
-    },
-    onTimeoutError(functionName) {
-      throw new Error(`[vitest-pool]: Timeout calling "${functionName}"`)
-    },
-  })
+  )
 
   project.ctx.onCancel(reason => rpc.onCancel(reason))