Core Web Vitals Explained: LCP, INP, and CLS
Google cares about real-user speed, not a green PageSpeed badge. What to measure and fix from $399.
Core Web Vitals are three metrics Google uses for real-device experience. Poor scores hurt SEO and conversion: every second of delay costs leads.
The three metrics
LCP (Largest Contentful Paint)
How fast main content appears (hero, large image). Target: ≤ 2.5s. Common causes: heavy images, blocking JS, slow server.
INP (Interaction to Next Paint)
How responsive the UI feels on tap and input. Target: ≤ 200ms. Heavy scripts, extra re-renders, third-party widgets.
CLS (Cumulative Layout Shift)
Does layout jump while loading? Target: ≤ 0.1. Ads without dimensions, fonts without fallback, lazy-load without placeholders.
PageSpeed ≠ reality
Lab tests on fast Wi-Fi don't replace CrUX — data from your visitors' phones. Use Search Console and field data.
Performance sprint
- Before/after baseline on priority URLs
- Bottleneck map ranked by impact
- Fix pack: images, JS, fonts, cache
- Anti-regression checklist for future releases
Timeline: 3–14 days. From $399. Start with one landing page before scaling paid traffic.
Don't load 12 analytics scripts then wonder about INP. Remove bloat first — micro-optimizations second.
"A fast site isn't a vanity metric. It's lower bounce rates and cheaper ads."