The React Compiler (formerly "React Forget") shipped stable in React 19. The promise? Automatic memoization — no more hand-crafting useMemo , useCallback , and React.memo wrappers. Just write plain React, and the compiler handles the rest. But does it actually hold up? I ran a battery of benchmarks across real-world-ish scenarios to find out. What the React Compiler Actually Does Before we dive into numbers, a quick clarification. The React Compiler is a build-time Babel/SWC transform that analyzes your component tree and automatically inserts memoization where it's safe to do so. It rewrites your components to cache computed values and prevent unnecessary re-renders — all at compile time. useMemo and useCallback , by contrast, are runtime hooks that you manually place to signal: "cache this between renders." They're solving the same problem, but at different layers of the stack.…