Core Web Vitals & Optimization Strategies:
- Google Core Web Vitals measure real-world user experience across loading speed, interactivity responsiveness, and visual stability.
1. Largest Contentful Paint (LCP) - Loading Performance:
- Measures when the largest visible content element (hero image, video poster, or large heading) finishes rendering.
- Target: Under 2.5 seconds.
- Optimizations: Use CDN edge caching, compress images to WebP/AVIF, preload hero images (), and eliminate render-blocking CSS/JavaScript.
2. Interaction to Next Paint (INP) - Interactivity (Replaced FID):
- Measures the latency of all user interactions (clicks, taps, keystrokes) throughout the page lifecycle, reporting the worst delay between input and visual frame update.
- Target: Under 200 milliseconds.
- Optimizations: Break up long JavaScript tasks using scheduler.yield() or Web Workers, debounce heavy event handlers, and avoid synchronous layout recalculations.
3. Cumulative Layout Shift (CLS) - Visual Stability:
- Measures unexpected layout shifting where page elements suddenly move around as asynchronous assets load.
- Target: Score under 0.1.
- Optimizations: Always set explicit width and height attributes on images/videos, reserve layout space for dynamic ad banners, and use CSS font-display: optional to avoid FOIT/FOUT font swaps.