nextjs-turbopack

name	nextjs-turbopack
description	Next.js 16+ and Turbopack — incremental bundling, FS caching, dev speed, production builds, Server Fast Refresh, and when to fall back to webpack.

Next.js and Turbopack

Current version: Next.js 16.2.x (June 2026)

Next.js 16+ uses Turbopack as its default bundler for both development and production builds. Turbopack is an incremental bundler written in Rust that significantly speeds up dev startup, hot updates, and production build times.

When to Use

• Turbopack (default): Used for both next dev and next build. Faster cold start, HMR, and production builds, especially in large apps.
• Webpack (legacy fallback): Use only if you hit a Turbopack bug or rely on a webpack-only plugin. Disable Turbopack with --no-turbopack flag or set NEXT_DISABLE_TURBOPACK=1 environment variable.

Use when: developing or debugging Next.js 16+ apps, diagnosing slow dev startup or HMR, or optimizing production bundles.

How It Works

• Turbopack: Incremental bundler for both dev and production. Uses file-system caching so restarts and rebuilds are much faster (e.g. 5–14x on large projects).
• Default bundler: From Next.js 16, both next dev and next build use Turbopack unless explicitly disabled.
• File-system caching: Restarts reuse previous work; cache is typically under .next; no extra config needed for basic use.
• Server Fast Refresh (16.2+): Server Components now support fast refresh — edits to server components are reflected without a full page reload, preserving client state.
• Bundle Analyzer (Next.js 16.1+): Experimental Bundle Analyzer to inspect output and find heavy dependencies; enable via config or experimental flag (see Next.js docs for your version).

Examples

Commands

next dev
next build
next start

Usage

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.

Best Practices

• Stay on Next.js 16.2.x or later for stable Turbopack dev + production builds and Server Fast Refresh.
• If dev is slow, ensure you're on Turbopack (default) and that the cache isn't being cleared unnecessarily.
• For production bundle size issues, use the official Next.js bundle analysis tooling for your version.
• If you need to fall back to webpack, prefer NEXT_DISABLE_TURBOPACK=1 in CI or --no-turbopack locally.