[4.1.1] Tailwindcss v4.1.x too slower，twenty times slower than 4.0.x

[zyycn]

What version of Tailwind CSS are you using?

v4.1.x

What build tool (or framework if it abstracts the build tool) are you using?

Vite 6.2.4

What version of Node.js are you using?

v22.14.0

What browser are you using?

Chrome,

What operating system are you using?

Windows

Reproduction URL

https://github.com/zyycn/tailwindcss-v4.1.x-speed

Describe your issue

Tailwindcss v4.1.x ，hot update in 4.0.x is between 100ms-200ms，but in 4.1.x is 2.3s-3s !

[MGRatEJOT]

Same here. When using Tailwindcss 4.1.X with Vite the HMR time is increased from ~100ms to ~1.5s on my machine.

[wongjn]

Might be fixed by #17511

[zyycn]

Might be fixed by #17511

maybe ，i just use this code fix it right now

@import 'tailwindcss' source(none);
@source '../';

@MGRatEJOT hi, use it improve tailwindcss speed

[leeuwd]

Thanks!

Discovered this issue since I was initially looking at Next.js and/or Turbopack compilation issues (see vercel/next.js#77624).

Turns out it was indeed Tailwind CSS v4 (for me).

The context is a Turborepo monorepo with Next.js 15.2.4.

Fix

Before

@import 'tailwindcss';

@source './../components/**/*.{ts,tsx}';
@source './../../../**/apps/{data,web}/**/*.{ts,tsx}';

After

@import 'tailwindcss' source(none);

@source '../components';
@source '../../../../apps/data';
@source '../../../../apps/web';

[philipp-spiess]

Hey folks! Do you mind running the dev server with the DEBUG=1 env variable set and posting the timing information it prints there? Trying to confirm that it's the same part that we want to address via #17511

[leeuwd]

Hey folks! Do you mind running the dev server with the DEBUG=1 env variable set and posting the timing information it prints there? Trying to confirm that it's the same part that we want to address via #17511

Sure thing.

Before (very slow compilation)

web:dev: [0.17ms] [@tailwindcss/postcss] ../../packages/ui/src/lib/miistafontsans_b506600b.module.css
web:dev: [0.15ms]   ↳ Quick bail check
web:dev: 
web:dev: 
web:dev: [492.34ms] [@tailwindcss/postcss] ../../packages/ui/src/styles/globals.css
web:dev: [  0.02ms]   ↳ Quick bail check
web:dev: [116.58ms]   ↳ Setup compiler
web:dev: [  0.26ms]     ↳ PostCSS AST -> Tailwind CSS AST
web:dev: [116.29ms]     ↳ Create compiler
web:dev: [  0.60ms]   ↳ Register full rebuild paths
web:dev: [  3.86ms]   ↳ Setup scanner
web:dev: [ 20.83ms]   ↳ Scan for candidates
web:dev: [315.98ms]   ↳ Register dependency messages
web:dev: [ 26.14ms]   ↳ Build utilities
web:dev: [  2.93ms]   ↳ Transform Tailwind CSS AST into PostCSS AST
web:dev: [  4.91ms]   ↳ Update PostCSS AST
web:dev: 
web:dev: 
web:dev: [0.23ms] [@tailwindcss/postcss] ../../packages/ui/src/lib/[redacted].module.css
web:dev: [0.22ms]   ↳ Quick bail check
web:dev: 
web:dev:  ✓ Compiled /[locale] in 6.8s

After (so when it works fine, with the fix as described at #17522 (comment)

web:dev: [331.25ms] [@tailwindcss/postcss] ../../packages/ui/src/styles/globals.css
web:dev: [  0.04ms]   ↳ Quick bail check
web:dev: [118.56ms]   ↳ Setup compiler
web:dev: [  0.36ms]     ↳ PostCSS AST -> Tailwind CSS AST
web:dev: [118.17ms]     ↳ Create compiler
web:dev: [  0.13ms]   ↳ Register full rebuild paths
web:dev: [  6.13ms]   ↳ Setup scanner
web:dev: [ 29.00ms]   ↳ Scan for candidates
web:dev: [142.73ms]   ↳ Register dependency messages
web:dev: [ 25.56ms]   ↳ Build utilities
web:dev: [  3.30ms]   ↳ Transform Tailwind CSS AST into PostCSS AST
web:dev: [  5.45ms]   ↳ Update PostCSS AST
web:dev: 
web:dev: 
web:dev: [0.16ms] [@tailwindcss/postcss] ../../packages/ui/src/lib/[redacted]_b506600b.module.css
web:dev: [0.15ms]   ↳ Quick bail check
web:dev: 
web:dev: 
web:dev: [0.02ms] [@tailwindcss/postcss] ../../packages/ui/src/lib/[redacted].module.css
web:dev: [0.01ms]   ↳ Quick bail check
web:dev: 
web:dev:  ✓ Compiled in 423ms

My setup:

Using Tailwind CSS 4.1.1.

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.4.0: Wed Mar 19 21:16:34 PDT 2025; root:xnu-11417.101.15~1/RELEASE_ARM64_T6000
  Available memory (MB): 16384
  Available CPU cores: 10
Binaries:
  Node: 22.14.0
  npm: 11.2.0
  Yarn: N/A
  pnpm: 10.7.1
Relevant Packages:
  next: 15.2.4 // Latest available version is detected (15.2.4).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.2
Next.js Config:
  output: N/A

[zyycn]

Hey folks! Do you mind running the dev server with the DEBUG=1 env variable set and posting the timing information it prints there? Trying to confirm that it's the same part that we want to address via #17511

https://github.com/zyycn/tailwindcss-v4.1.x-speed hi , use this repository，here is debug info.

[philipp-spiess]

@leeuwd Thanks! This is indeed consistent with what we'd expect to be resolved by #17511. We'll post an update there as soon as this fix is out, probably later today!

[HasanMothaffar]

@leeuwd I can confirm your fix works for me. Compilation times went from 10-20 seconds to ~300ms. I'm using Next.js 15.2.4 with Turbopack.

[RobinMalfait]

Hey!

This should be fixed by #17511 and will be available in the next release (later today).