On this page 8 sections
Short answer: Core Web Vitals are three Google measurements of real user experience: LCP (how fast the main content loads, aim for under 2.5 seconds), INP (how quickly the page responds to taps and clicks, aim for under 200 milliseconds) and CLS (how much the layout jumps around, aim for under 0.1). Good scores help rankings a little and conversions a lot.
A slow website loses visitors before they read a word. Here is what Google measures and how I make client sites fast.
The three Core Web Vitals
| Metric | Measures | Good | Needs work | Poor |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | Loading speed of the main content | ≤ 2.5 s | 2.5 to 4 s | > 4 s |
| INP (Interaction to Next Paint) | Responsiveness to clicks and taps | ≤ 200 ms | 200 to 500 ms | > 500 ms |
| CLS (Cumulative Layout Shift) | Visual stability | ≤ 0.1 | 0.1 to 0.25 | > 0.25 |
Google uses real-user data from Chrome, measured at the 75th percentile, so most visitors need a good experience, not just you on fast Wi-Fi.
How to test your site
- PageSpeed Insights: real-user data plus a lab test and suggestions
- Google Search Console: the Core Web Vitals report shows problem pages across your site (setup guide)
- Chrome DevTools: the Performance and Lighthouse panels for debugging
- Test on a mid-range phone on mobile data. That is what many of your visitors use.
How to fix LCP (slow loading)
- Compress images and use modern formats like WebP or AVIF. This is often the biggest win. This site converts every screenshot to WebP at three sizes automatically.
- Serve the right image size with
srcsetso phones don’t download desktop images - Preload the hero image and key fonts
- Use good hosting and a CDN
- Cache pages so the server doesn’t rebuild them each time
- Remove render-blocking CSS and JavaScript from the top of the page
How to fix INP (slow interactions)
- Ship less JavaScript. Remove unused plugins, sliders and trackers.
- Break up long tasks so the browser can respond between them
- Delay non-essential scripts like chat widgets and analytics until after load
- Avoid heavy page builders where a few lines of CSS would do
How to fix CLS (jumping layout)
- Always set width and height on images and videos
- Reserve space for ads, embeds and banners
- Use font-display: swap with matched fallback fonts
- Don’t insert content above existing content after the page loads
Do Core Web Vitals affect SEO?
Yes, as part of Google’s page experience signals, but content relevance matters more. A fast page with weak content won’t outrank a slower page that answers the question far better. Think of speed as a tie-breaker for rankings and a big lever for conversions: faster sites get more enquiries and sales.
WordPress sites
Most slow WordPress sites suffer from heavy themes, too many plugins and huge images. My WordPress speed guide has a step-by-step fix list.
Frequently asked questions
What is a good PageSpeed score?
The score is a lab estimate. Focus on passing the three Core Web Vitals with real-user data. A 90+ lab score is nice, but real visitors matter more.
Why is my site fast on desktop but slow on mobile?
Phones have slower processors and networks. Large images and heavy JavaScript hurt mobile far more than desktop.
What replaced FID?
INP (Interaction to Next Paint) replaced FID (First Input Delay) as the responsiveness metric in 2024.
Can you make my website faster?
Yes. Speed optimization is part of every site I build, and I fix slow existing sites too. Get in touch.
Written by Syed Imran Murtaza
Freelance software engineer and web developer in Karachi, Pakistan (also known as CtrlAltImran). I build websites, web apps, custom WordPress plugins and AI tools for clients worldwide. About me · Hire me · My work