Scaling a React application for millions of users requires more than just adding servers. It requires a thoughtful architecture from day one.
Server-Side Rendering vs Static Generation
Next.js gives you the best of both worlds. Use Static Site Generation (SSG) for pages with content that doesn't change often, and Server-Side Rendering (SSR) for dynamic, user-specific content.
Caching Strategies
Implement aggressive caching at every layer: CDN-level caching for static assets, API response caching with Redis, and client-side caching with React Query or SWR.
The key insight is to push computation as close to the edge as possible, reducing latency and server load simultaneously.