Link to the code that reproduces this issue

https://github.com/foxable/reproduction-next15-memory-consumption

To Reproduce

1. Create production build pnpm build
2. Start production mode: pnpm start
3. Monitor memory consumption of next-server process

To generate more or less pages, edit generate-pages.mjs and run pnpm generate-pages.

Current vs. Expected behavior

Compared to Next.js 14 (try Next.js 14 reproduction for comparison), the production mode in Next.js 15 shows a significantly increased memory consumption, which also significantly increases with the number of pages:

Memory consumption in production mode

While in absolute numbers, the memory consumption is still arguably low, the relative increase is significant, as well as the additional memory consumption for each page.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Thu, 13 Mar 2025 18:12:00 +0000
  Available memory (MB): 31793
  Available CPU cores: 16
Binaries:
  Node: 22.13.0
  npm: 10.9.2
  Yarn: 1.22.22
  pnpm: 10.6.3
Relevant Packages:
  next: 15.2.3 // Latest available version is detected (15.2.3).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.8.2
Next.js Config:
  output: N/A

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

Runtime

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

next start (local)

Additional context

I noticed the increased memory consumption after migrating a project with ~120 pages from Next.js 14.2.24 to Next.js 15. I was also able to reproduce the increased memory consumption with all minor version currently available for Next.js 15.