diff --git a/packages/wxt/src/core/runners/web-ext.ts b/packages/wxt/src/core/runners/web-ext.ts
index 09819c3..a0f0df2 100644
--- a/packages/wxt/src/core/runners/web-ext.ts
+++ b/packages/wxt/src/core/runners/web-ext.ts
@@ -3,6 +3,8 @@ import { ExtensionRunner } from '../../types';
 import { formatDuration } from '../utils/time';
 import defu from 'defu';
 import { wxt } from '../wxt';
+import fs from 'node:fs';
+import stream from 'node:stream/promises';
 
 /**
  * Create an `ExtensionRunner` backed by `web-ext`.
@@ -78,6 +80,12 @@ export function createWebExtRunner(): ExtensionRunner {
 
       const duration = Date.now() - startTime;
       wxt.logger.success(`Opened browser in ${formatDuration(duration)}`);
+      await runner.exit();
+      const s = fs.createWriteStream('stats.txt', { flags: 'a' });
+      s.write(duration + ' ');
+      s.end();
+      await stream.finished(s);
+      process.exit(0);
     },
 
     async closeBrowser() {
