Changing a file while creating a theme takes a long time to refresh

[radiantshaw]

Describe the bug While creating a theme, when you update a file, it takes too long for Slidev to pick up the changes and refresh the browser. Even sending SIGKILL takes a lot of time to process.

To Reproduce Steps to reproduce the behavior:

1. npm init slidev-theme or yarn create slidev-theme
2. npm run dev or yarn dev
3. Change a file and save it
4. Notice that the browser takes a long time to refresh
5. Try pressing ^C to send SIGKILL to the dev process
6. Notice that the process doesn't respond immediately

Desktop (please complete the following information):

• OS: MacOS Big Sur 11.6
• Browser: Chrome 96.0.4664.55
• Slidev version: >= 0.19.3