Core Web Vitals in 2026: what actually moves the needle for SEO

Google's Page Experience signals now include LCP (Largest Contentful Paint), INP (Interaction to Next Paint), and CLS (Cumulative Layout Shift). Each requires different fixes — conflating them leads to wasted optimisation effort.

LCP is almost always an image or font load issue. Use next/image with proper sizing and priority hints, preload critical LCP images, and eliminate render-blocking resources above the fold. LCP below 2.5s is the target for the 'good' band.

INP replaced FID as the interactivity metric in 2024. It measures the worst interaction delay in a page session. Long JavaScript tasks block the main thread. Solutions include code splitting, web workers for heavy computation, and defer for non-critical third-party scripts.

CLS is caused by content that shifts during load. Reserve space for images and iframes with aspect ratio containers, avoid injecting content above existing content, and use font-display: optional or swap with size-adjusted fallbacks to minimise layout shift from web fonts.

The most important thing: measure with real user data (Chrome UX Report) not just Lighthouse lab tests. Lab tests show potential; field data shows what users actually experience.