Next.js 16+ and Turbopack — incremental bundling, FS caching, dev speed, and when to use Turbopack vs webpack.
Next.js 16+ uses Turbopack by default for local development: an incremental bundler written in Rust that significantly speeds up dev startup and hot updates.
--webpack (or --no-turbopack depending on your Next.js version; check the docs for your release).next build) may use Turbopack or webpack depending on Next.js version; check the official Next.js docs for your version.Use when: developing or debugging Next.js 16+ apps, diagnosing slow dev startup or HMR, or optimizing production bundles.
next dev runs with Turbopack unless disabled..next; no extra config needed for basic use.next dev
next build
next start
Run next dev for local development with Turbopack. Use the Bundle Analyzer (see Next.js docs) to optimize code-splitting and trim large dependencies. Prefer App Router and server components where possible.