15X Build Slowdown in the Latest NextJS Version

[MartinXPN]

Link to the code that reproduces this issue

https://github.com/MartinXPN/next-slow-build-reproduction

To Reproduce

# You can run `yarn build` instead to see the execution time
npm run build     # (~500s) This will build the app with the latest Next.js version
npm uninstall next && npm install next@13.4.19 && rm -rf .next
npm run build     # (~35s) This will build the app with the previous Next.js version

Current vs. Expected behavior

It currently takes ~15x longer to build a project with a large client-side component compared to the previous NextJS version. This REALLY hurts the developer experience! It should take way quicker to build the whole project and produce the production build.

For this small project, it took ~500s to build with the latest Next.js version, while it used to take only ~40 with the 13.4.9 version.

Using the latest version of NextJS actually resulted in a 20x build slowdown on one of my actual projects (not the reproduction above) making each build ~40 minutes instead of 2. Imagine how terrible it is to wait for 40 minutes for every minor change to hit production!

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.4.0: Wed Feb 21 21:45:49 PST 2024; root:xnu-10063.101.15~2/RELEASE_ARM64_T6020
Binaries:
  Node: 20.10.0
  npm: 10.2.3
  Yarn: 1.22.21
  pnpm: N/A
Relevant Packages:
  next: 14.1.3
  eslint-config-next: 14.0.3
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.4.2
Next.js Config:
  output: N/A

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

Not sure, App Router, Dynamic imports (next/dynamic)

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

next build (local), Vercel (Deployed)

Additional context

I've also reproduced this with a large form using react-hook-form and zod.

There was a recent fix that was supposed to fix this issue but actually had no effect on my projects.

This is the same project with the same dependencies (NextJS latest version VS 13.4.9). Imagine the pain of waiting 40 minutes every time you push to production (while it used to take only 2 minutes).

[samvel1024]

I have the same issue after upgrading the library as well.

[hrachgalstyan]

I encountered the identical problem following the library upgrade too.

[HakobjanyanHayk]

Any updates on this?

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[ngwallace]

going through the same issue after upgarding the library

[MartinXPN]

Seems like the latest release of NextJS (14.2) fixed this issue partially. The project currently builds just 2X slower. Yet, deploying it to Vercel takes forever. The longest step seems to be the one that creates the serverless functions (used to be only a couple of seconds):

Created all serverless functions in: 16:32.559 (m:ss.mmm)