Scaling a React App (SSR, Caching, Performance) – What I Actually Do to Handle Thousands of Users
Frontend · 2025-10-10 · 48 min · Barthez Kenwou
A React app that slows down at 1,000 active users? Here's the most complete scaling guide I've written: web rendering fundamentals (TTFB, hydration, Core Web Vitals), per-route rendering strategy (SSG/ISR/SSR/Edge/Partial Prerendering) including the SSG-at-scale trap, layered caching with tag-based invalidation and cache-stampede protection, React Server Components beyond bundle reduction (the real HTTP streaming mechanism, serialization pitfalls, waterfalls, Server Actions), the real limits of Edge Rendering, the hidden cost of prefetching, SEO facing streaming, the middleware trap, and most importantly, the part almost nobody covers: the backend behind your React app. Ultra-detailed guide with code, RUM monitoring, k6 load testing, five real production incidents, a discernment section, and a real case where we went from 3s TTFB to <300ms while cutting server costs by 45%.
Tags : ReactScaling, NextJS, SSR, ISR, Caching, Performance, ReactServerComponents, EdgeRendering, CoreWebVitals, PartialPrerendering, DevOps