Performance is not just a rendering problem. It is an algorithmic problem. Every extra loop, every unnecessary diff, and every hidden listener steals budget from the user.
Lead with measurement. Define your frame budget, profile the main thread, and move anything expensive off the critical path.
RENDER_BUDGETS
Modern UIs are data-heavy, and the easiest mistake is to treat the DOM like a free resource. Virtualization keeps lists cheap. Memoization keeps components stable. And batching updates keeps the main thread breathing.
Think in budgets: a frame gives you about 16ms. Spend it on what the user can see and feel, not on work that can wait.
"The fastest interaction is the one that never blocks the main thread."
BACKGROUND_WORK
Push expensive work off the critical path. Web Workers, idle callbacks, and precomputation keep the UI responsive while still delivering rich functionality.
- Virtualize long lists and tables; never render what you cannot see.
- Use
requestIdleCallbackor workers for heavy transforms. - Profile and remove listeners that fire on scroll and resize.
Algorithmic efficiency is a UX feature. It preserves battery, reduces heat, and makes complex applications feel effortless.