Next.js 15.1: Turbopack is Now Stable

After months of beta testing, Turbopack is officially stable in Next.js 15.1. Here's what you need to know.

10x Faster Cold Starts

Turbopack delivers dramatically faster development server startup times compared to Webpack. In our testing, a large application that took 30 seconds to start now boots in under 3 seconds.

This improvement comes from:

• Incremental compilation from the start
• Better caching strategies
• Rust-based bundling engine

Improved HMR

Hot Module Replacement is now nearly instantaneous, even in large codebases. Changes are reflected in the browser in milliseconds.

Migration Guide

To enable Turbopack, update your dev script:

{
  "scripts": {
    "dev": "next dev --turbopack"
  }
}

App Router Enhancements

This release also brings improvements to the App Router:

• New unstable_cache API for data caching
• Improved parallel route handling
• Better error overlay with source maps

Performance Numbers

| Metric | Webpack | Turbopack | |--------|---------|-----------| | Cold start | 30s | 3s | | HMR | 1.2s | 50ms | | Build time | 120s | 45s |

What's Next

The team is now working on production build support for Turbopack, expected in Next.js 16.