diff --git a/test/vitest-performance-config.test.ts b/test/vitest-performance-config.test.ts
index 213d73bd723..4766b6cf272 100644
--- a/test/vitest-performance-config.test.ts
+++ b/test/vitest-performance-config.test.ts
@@ -22,6 +22,43 @@ describe("loadVitestExperimentalConfig", () => {
     });
   });
 
+  it("disables the filesystem module cache by default on Windows", () => {
+    const originalRunnerOs = process.env.RUNNER_OS;
+    process.env.RUNNER_OS = "Windows";
+    try {
+      expect(loadVitestExperimentalConfig({ RUNNER_OS: "Windows" })).toEqual({});
+    } finally {
+      if (originalRunnerOs === undefined) {
+        delete process.env.RUNNER_OS;
+      } else {
+        process.env.RUNNER_OS = originalRunnerOs;
+      }
+    }
+  });
+
+  it("still allows enabling the filesystem module cache explicitly on Windows", () => {
+    const originalRunnerOs = process.env.RUNNER_OS;
+    process.env.RUNNER_OS = "Windows";
+    try {
+      expect(
+        loadVitestExperimentalConfig({
+          RUNNER_OS: "Windows",
+          OPENCLAW_VITEST_FS_MODULE_CACHE: "1",
+        }),
+      ).toEqual({
+        experimental: {
+          fsModuleCache: true,
+        },
+      });
+    } finally {
+      if (originalRunnerOs === undefined) {
+        delete process.env.RUNNER_OS;
+      } else {
+        process.env.RUNNER_OS = originalRunnerOs;
+      }
+    }
+  });
+
   it("allows disabling the filesystem module cache explicitly", () => {
     expect(
       loadVitestExperimentalConfig({
diff --git a/vitest.performance-config.ts b/vitest.performance-config.ts
index 3211efbf6d4..a94e089b599 100644
--- a/vitest.performance-config.ts
+++ b/vitest.performance-config.ts
@@ -10,6 +10,14 @@ const isDisabled = (value: string | undefined): boolean => {
   return normalized === "0" || normalized === "false";
 };
 
+const isWindowsEnv = (env: EnvMap, platform: NodeJS.Platform): boolean => {
+  if (platform === "win32") {
+    return true;
+  }
+  const runnerOs = env.RUNNER_OS?.trim().toLowerCase();
+  return runnerOs === "windows";
+};
+
 export function loadVitestExperimentalConfig(env: EnvMap = process.env): {
   experimental?: {
     fsModuleCache?: true;
@@ -22,8 +30,12 @@ export function loadVitestExperimentalConfig(env: EnvMap = process.env): {
     importDurations?: { print: true };
     printImportBreakdown?: true;
   } = {};
+  const windowsEnv = isWindowsEnv(env, process.platform);
 
-  if (!isDisabled(env.OPENCLAW_VITEST_FS_MODULE_CACHE)) {
+  if (!windowsEnv && !isDisabled(env.OPENCLAW_VITEST_FS_MODULE_CACHE)) {
+    experimental.fsModuleCache = true;
+  }
+  if (windowsEnv && isEnabled(env.OPENCLAW_VITEST_FS_MODULE_CACHE)) {
     experimental.fsModuleCache = true;
   }
   if (isEnabled(env.OPENCLAW_VITEST_IMPORT_DURATIONS)) {