This is Vercel's internal performance playbook turned into 45 concrete rules across 8 priority categories, from eliminating request waterfalls to optimizing re-renders. Use it when writing or reviewing React and Next.js code where performance matters. The categorization by impact (CRITICAL for bundle size and async waterfalls, down to LOW for advanced patterns) makes it easy to know what to fix first. Each rule has a prefix like `async-parallel` or `bundle-barrel-imports` and includes both bad and good code examples. It's opinionated in the right way: stop using barrel imports, use React.cache() for deduplication, preload on hover instead of on mount. If you ship React apps on Vercel or anywhere else, this codifies the patterns their engineering team actually follows.
npx skills add https://github.com/calcom/cal.com --skill vercel-react-best-practices