What problem does it solve? Developers working with Next.js 16+ often face slow dev startup, confusing bundler choices between Turbopack and webpack, and unclear production build behavior. This Skill provides concrete guidance on when to use Turbopack, how its file-system caching works, and how to diagnose slow HMR or bloated bundles. ## Core Features & Use Cases - Bundler Selection Guidance: Clarifies when to use Turbopack (default dev) versus webpack (legacy fallback via --webpack flag) and how production builds differ by Next.js version. - Dev Performance Optimization: Explains incremental bundling and file-system caching under .next that makes restarts 5-14x faster on large projects. - Bundle Analysis: Covers the experimental Bundle Analyzer in Next.js 16.1+ for inspecting output and trimming heavy dependencies. - Use Case: Your Next.js app's dev server takes minutes to start. Use this Skill to confirm Turbopack is active, verify the cache isn't being cleared, and apply Bundle Analyzer insights to reduce cold start time. ## Quick Start Ask the AI to explain why my Next.js 16 dev server is slow and whether I should use Turbopack or webpack for my project.