Performance

Performance is a UX problem with measurable, perception-keyed budgets.

• Core Web Vitals:
  • LCP (Largest Contentful Paint) — loading; the main content should render fast. Budget: ≤2.5s.
  • INP (Interaction to Next Paint) — interactivity; replaced FID in 2024. Budget: ≤200ms.
  • CLS (Cumulative Layout Shift) — visual stability; no content jumping. Budget: ≤0.1.
• RAIL Model: Performance budgets keyed to human perception:
  • Response — react to input in <100ms.
  • Animation — 60fps, ~16ms per frame.
  • Idle — chunk non-critical work into idle time.
  • Load — become interactive fast; defer the rest.

How to apply