Core Web Vitals in 2026: What They Are and Why They Still Matter
Google's Core Web Vitals are a set of real-world performance metrics that directly affect your search rankings. Here's what each one means and how to fix them.
Google uses Core Web Vitals as a ranking signal. That means a slow website doesn't just frustrate users — it actively hurts your position in search results.
Here's what each metric means and what you can do about it.
LCP — Largest Contentful Paint
What it measures: How long it takes for the largest visible element (usually a hero image or heading) to load.
Good score: Under 2.5 seconds.
Common causes of poor LCP:
- Large, unoptimised hero images
- Slow server response times
- Render-blocking JavaScript
How to fix it:
- Use
next/imagefor automatic image optimisation and lazy loading - Serve images in WebP or AVIF format
- Use SSG or SSR so the browser gets real HTML immediately
CLS — Cumulative Layout Shift
What it measures: How much the page layout shifts unexpectedly while loading. Ever clicked a button just as an ad loaded above it and accidentally clicked the ad? That's CLS.
Good score: Under 0.1.
Common causes:
- Images without explicit width and height
- Fonts that swap in late (FOUT)
- Dynamically injected content above the fold
How to fix it:
- Always set width and height on images
- Use
font-display: optionalor preload your fonts - Reserve space for dynamic content with CSS
INP — Interaction to Next Paint
What it measures: How quickly your page responds to user interactions (clicks, taps, keyboard input). INP replaced FID in 2024.
Good score: Under 200ms.
Common causes:
- Heavy JavaScript executing on the main thread
- Unoptimised event handlers
- Large React re-renders
How to fix it:
- Code-split large JavaScript bundles
- Use
useMemoanduseCallbackto prevent unnecessary re-renders - Defer non-critical scripts
How to Check Your Scores
- Run a PageSpeed Insights report on your URL
- Check the Field Data section (real user data) — not just Lab Data
- Use Google Search Console → Core Web Vitals report for site-wide trends
The Honest Reality
Most sites we audit fail on LCP. The fix is almost always the same: move from client-side rendering to SSG/SSR, optimise images, and remove render-blocking scripts.
If your scores are in the red, we can help. We run a free performance audit as part of every project scoping call.