Core Web Vitals are critical for both rankings and user experience. If your site fails these metrics, it can directly impact your visibility in search engines.
This guide shows developers exactly how to fix them.
What Are Core Web Vitals?
Core Web Vitals measure real-world user experience:
- Largest Contentful Paint (LCP) → loading performance
- Interaction to Next Paint (INP) → responsiveness
- Cumulative Layout Shift (CLS) → visual stability
Fixing Largest Contentful Paint (LCP)
Common Problems:
- Slow server response time
- Large images or videos
- Render-blocking CSS/JS
Solutions:
- Use server-side caching (Symfony HTTP cache / Drupal cache)
- Optimize images (WebP/AVIF)
- Preload critical assets:
<link rel="preload" as="image" href="hero.webp">Fixing Interaction to Next Paint (INP)
Common Problems:
- Heavy JavaScript execution
- Too many event listeners
- Blocking main thread
Solutions:
- Split JavaScript bundles
- Defer non-critical JS
<script src="app.js" defer></script>- Use web workers for heavy tasks
Fixing Cumulative Layout Shift (CLS)
Common Problems:
- Images without dimensions
- Ads or dynamic content loading late
Solutions:
- Always define width and height:
<img src="image.jpg" width="800" height="600">- Reserve space for dynamic elements
- Avoid injecting content above existing content
Testing Your Fixes
Use tools like:
- Lighthouse
- Chrome DevTools
- Real user monitoring (RUM)
Internal Linking Tip
For a full technical audit, check our complete Technical SEO Checklist for Developers.
Final Thoughts
Improving Core Web Vitals is one of the fastest ways to boost both SEO and UX. Small fixes can lead to big ranking improvements.