CI Builds Get Massive Speedup
`bun install` with caching cut CI builds from 8 minutes to under 2 minutes vs `npm ci`. Meanwhile, Next.js with React Compiler and partial prerendering is delivering 40% LCP improvements in production.
The speed of `bun install` stems from a fundamental redesign of the package installation process, treating it as a systems programming challenge rather than a JavaScript one. Written in the low-level language Zig, Bun minimizes expensive system calls—the communication between the application and the operating system—making around 165,000 calls in a benchmark where npm required nearly 1 million. Bun's architecture avoids the overhead of a JavaScript runtime like Node.js for file operations, communicating directly with the operating system's kernel. It also uses platform-specific optimizations, like `clonefile` on macOS, to copy files almost instantly. A binary lockfile format and other cache-friendly data structures further reduce parsing time compared to text-based files used by other managers. On the frontend, the React Compiler, previously codenamed "React Forget," provides performance gains by automating optimization. It acts as a build-time tool that automatically memoizes components, eliminating the need for developers to manually use hooks like `useMemo` and `useCallback` to prevent unnecessary re-renders. This automated memoization means the compiler analyzes code and caches the output of components, ensuring they only re-render when their inputs have semantically changed. This simplifies codebases and makes applications faster and more efficient by default, with support integrated into Next.js. Next.js's partial prerendering (PPR) combines the benefits of static site generation (SSG) and server-side rendering (SSR). It serves an initial, static HTML shell of a page from the edge, which loads almost instantly for the user. This directly improves Core Web Vitals like Time to First Byte (TTFB) and First Contentful Paint (FCP). Dynamic parts of the page are wrapped in a React `<Suspense>` boundary, which shows a fallback or loading state. While the user views the static shell, the dynamic data is fetched and streamed in to replace the placeholders, improving the Largest Contentful Paint (LCP) without blocking the initial render.
