Core Web Vitals are a small set of real-user metrics that measure page loading (LCP), interactivity (INP), and visual stability (CLS). Improving them directly improves user experience and can affect search visibility.
What each metric means (quick)
LCP (Largest Contentful Paint): time until the main content is visible. Aim for ≤2.5s.
INP (Interaction to Next Paint): measures responsiveness during interactions.
CLS (Cumulative Layout Shift): measures unexpected layout movement; keep it low.
High-impact quick wins
Optimize images — serve modern formats (WebP/AVIF), resize server-side, and use responsive.
Defer non-critical JavaScript — split bundles, lazy-load third-party scripts, and remove unused code.
Font loading hygiene — preload key fonts, use
font-display: swap, and limit font weights.Server & CDN speed — reduce Time to First Byte with edge caching and a CDN for global users
Practical measurement approach
Use Field data (Real User Monitoring / Search Console) to understand real-world behaviour.
Use Lab tools (Lighthouse) for reproducible checks during development.
Prioritize fixes by impact vs effort: start with things that affect LCP and CLS for your most important pages.
Checklist to ship improvements
Add image optimization pipeline (responsive sizes + modern formats).
Audit and lazy-load third-party scripts.
Preload and subset fonts; provide fallbacks.
Small, targeted changes typically yield the biggest UX gains. Track metrics before/after, and prioritize the pages that deliver business value.
