Tailwindcss Performance

Tailwind CSS Performance Optimization

v4 Performance Improvements

Tailwind CSS v4 features a completely rewritten engine in Rust:

Metric	v3	v4
Full builds	Baseline	Up to 5x faster
Incremental builds	Milliseconds	Microseconds (100x+)
Engine	JavaScript	Rust

JIT (Just-In-Time) Compilation

How JIT Works

JIT generates styles on-demand as classes are discovered in your files:

1. Scans source files for class names
2. Generates only the CSS you use
3. Produces minimal, optimized output

v4: Always JIT

Unlike v3, JIT is always enabled in v4—no configuration needed:

@import "tailwindcss";
/* JIT is automatic */

Content Detection

Automatic Detection (v4)

v4 automatically detects template files—no content configuration required:

/* v4 - Works automatically */
@import "tailwindcss";

Explicit Content (v4)

If automatic detection fails, specify sources explicitly:

@import "tailwindcss";
@source "./src/**/*.{html,js,jsx,ts,tsx,vue,svelte}";
@source "./components/**/*.{js,jsx,ts,tsx}";

Excluding Paths

@source not "./src/legacy/**";

Tree Shaking