Next.js 15.3: Turbopack Alpha Speeds Up Builds by 83%

Next.js 15.3 has arrived, and the biggest news is the alpha release of Turbopack for production builds. While the dev version of Turbopack has been around for a while, production support is now being tested. Benchmarks show 28%–83% faster builds depending on core count, making it a serious contender to replace Webpack in future versions.

The update includes experimental support for Rspack, a Webpack-compatible alternative with better performance. It’s available via a next-rspack adapter and backed by a community effort in collaboration with the Rspack team.

Routing is now more flexible thanks to new navigation hooks. useLinkStatus and onNavigate allow custom loading indicators, route cancellation, and improve UX during client-side navigation.

Next.js also adds an instrumentation-client.ts file, letting developers run monitoring or analytics scripts before the app hydrates. This is great for critical path performance tracking or early error reporting, which previously required hacks or delayed scripts.

Additional smaller changes include:

• The TypeScript plugin has been improved for better performance in large codebases.
• next/image now supports sizes="100vw" by default in fill mode, helping reduce layout shifts.
• Middleware and instrumentation files now support .cts and .mts extensions.

Read the full release notes at Next.js blog.

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