With React 19 now mainstream and React 20 on the horizon, the focus has shifted entirely to "automatic optimization." The days of endlessly wrapping components in React.memo and useCallback are fading into history.
The React Compiler: Zero-Config Perf
The React Compiler (formerly "React Forget") is the biggest DX win of 2026. It automatically memos components during the build step.
- No Dependencies array: The compiler tracks dependencies implicitly.
- Fine-Grained Updates: Only the changed nodes update, not the whole component tree.
// Before (Manual)
const visibleTodos = useMemo(() => filterTodos(todos, tab), [todos, tab]);
// After (Compiler)
const visibleTodos = filterTodos(todos, tab); // Automatically memoized!
Server Components as Default
React Server Components (RSC) are no longer experimental—they are the architectural standard. By shifting the bulk of your application logic to the server, you ship significantly less JavaScript to the client. This leads to:
- Faster TTI: Time to Interactive drops drastically.
- Smaller Bundles: Your client-side bundle is now mostly interactive islands.
Concurrency & Suspense
Concurrent rendering features are now stable and widely used. Suspense for data fetching is the norm, enabling specialized loading states and transitions that don't block the UI.
In 2026, React isn't just a UI library; it's a full-stack primitive for the modern web.