Initial GET / takes 23.3s with Turbopack in Next.js 16.3.1

Link to the code that reproduces this issue

https://github.com/PluemStudio/nextjs-test

To Reproduce

1. Create a new Next.js project using pnpm:
   pnpm create next-app@latest my-app
2. Navigate into the project directory:
   cd my-app
3. Run the development server with Turbopack:
   pnpm run dev
4. Open http://localhost:3000 in your browser.
5. Check the terminal and observe that the first GET / request takes around 23.3 seconds (with next.js compilation taking 23.1s).

Current vs. Expected behavior

When running pnpm run dev with Turbopack on a brand new, boilerplate Next.js project, the server starts instantly ("Ready in 389ms"), but the first initial page request (Cold Start) takes an abnormally long time (23.3 seconds).

Subsequent requests are fast (~30-40ms), but the first compilation of / spends 23.1s on "next.js" overhead, despite having no complex code or custom configurations.

The delay happens specifically inside the next.js internal compilation step (23.1s), whereas application-code only takes 204ms.

$: pnpm run dev  
$ next dev
▲ Next.js 16.3.1 (Turbopack)
- Local:         http://localhost:3000
- Network:       http://192.168.1.34:3000
✓ Ready in 389ms
✓ Running next.config.ts took 40ms

○ Compiling / ...
 GET / 200 in 23.3s (next.js: 23.1s, application-code: 204ms)
 GET / 200 in 31ms (next.js: 4ms, application-code: 27ms)
 GET / 200 in 42ms (next.js: 12ms, application-code: 30ms)
 GET / 200 in 32ms (next.js: 10ms, application-code: 22ms)

Provide environment information

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Pro
  Available memory (MB): 16306
  Available CPU cores: 12
Binaries:
  Node: 24.18.1
  npm: 11.16.0
  Yarn: N/A
  pnpm: 11.22.0
Relevant Packages:
  next: 16.3.1 // Latest available version is detected (16.3.1).
  eslint-config-next: N/A
  react: 19.2.8
  react-dom: 19.2.8
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Turbopack

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

No response

Start with the linked reproduction repository and run pnpm run dev on Windows 11 with Next.js 16.3.1 and Turbopack. Inspect the next dev initial compilation path for the first GET /, comparing its internal next.js time with the application-code time. Done means the boilerplate project's cold initial request no longer spends about 23 seconds compiling while subsequent requests remain fast.