Next.js 15 Features You Should Start Using Today

Next.js 15 is more than an incremental release — it's the version where the App Router matures into the obvious choice. From a stable React 19 compiler that eliminates manual memoization, to a reversed caching model that prevents stale-data bugs, to Turbopack hitting stable with up to 76% faster builds, the improvements compound. Here's what changed, why it matters, and how to start using it in production today.