According to Vercel, Next.js 14 offers significant performance boosts, including 53% faster local server startup and 94% faster code updates using Fast Refresh.
Additionally, 5,000 “next dev” integration tests have now passed with Turbopack, which is the underlying Rust engine for Next.js. Vercel says that developers should experience faster and more reliable performance using “next dev –turbo” now. The company also says that once 100% of tests pass with Turbopack, Turbopack will be moved to stable (currently 90% pass).
Also in this release, the Next.js team has improved the developer experience of authoring data mutations with the stable release of Server Actions, which allows you to define asynchronous server functions. You can use Server Actions to revalidate cached data, redirect to different routes, set and read cookies, and more.
Next.js 14 also includes a preview for Partial Prerending, which optimizes the compiler to handle dynamic content. It also does not require you to learn any new APIs to use. “We’ve heard your feedback. There’s currently too many runtimes, configuration options, and rendering methods to have to consider. You want the speed and reliability of static, while also supporting fully dynamic, personalized responses. Having great performance globally and personalization shouldn’t come at the cost of complexity,” Lee Robinson, VP of developer experience at Vercel, and Tim Neutkens, engineering manager for Next.js, wrote in a blog post.
Moving on, Vercel also decoupled blocking and non-blocking metadata and is deprecating several metadata options, including viewport, colorScheme, and themeColor. New metadata options have been added to replace those.
In addition to releasing Next.js 14, Vercel also announced the launch of a new course on Next.js Learn that covers the Next.js App Router, Tailwind CSS, optimizing fonts and images, creating layouts and pages, and more.