PERFORMANCE · SEO GLOSSARY
Core Web Vitals
Three Google metrics — LCP, INP, and CLS — that measure real-user loading, interactivity, and visual stability.
Definition
Core Web Vitals are three user-experience metrics that Google uses as page-experience ranking signals: Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). Google collects these from real Chrome users via the CrUX dataset and uses them — alongside other signals — in its ranking algorithm.
Why it matters for SEO
Failing Core Web Vitals can suppress rankings in competitive SERPs. More importantly, they measure the experience real users have: slow loading (LCP), sluggish interactions (INP), and elements jumping around during load (CLS) are directly correlated with higher bounce rates and lower conversion. Lab-only tests (Lighthouse) miss CDN caching, server location, and real device performance — which is why field data from CrUX matters more than synthetic scores.
How DeepSEOAnalysis checks this
The DeepSEOAnalysis audit fetches CrUX field data for the submitted domain (and falls back to the URL-level dataset if available). It flags LCP > 2.5s as critical, INP > 200ms as a warning, and CLS > 0.1 as a warning — matching Google's published thresholds. Lab scores from PageSpeed Insights supplement the field data but are not the primary signal.
Useful tools and resources
GLOSSARY
Related terms
performance
LCP (Largest Contentful Paint)
The time from page load start until the largest visible content element finishes rendering. Should be under 2.5 seconds.
Read definition →performance
CLS (Cumulative Layout Shift)
A Core Web Vital that measures unexpected visual shifts in page layout during load. Should be 0.1 or lower.
Read definition →See how your site scores on Core Web Vitals.
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