A slow website quietly loses customers. People leave pages that take too long to appear, jump around while loading or respond sluggishly to taps. Google measures these experiences with three numbers called Core Web Vitals. You do not need to be technical to understand them — or to ask your developer to fix them.
The three metrics in plain English
| Metric | What it measures | Good score |
|---|---|---|
| LCP – Largest Contentful Paint | How quickly the main content (hero image or headline) appears | 2.5 seconds or less |
| INP – Interaction to Next Paint | How quickly the page reacts when someone taps or clicks | 200 milliseconds or less |
| CLS – Cumulative Layout Shift | How much the layout jumps around while loading | 0.1 or less |
A page “passes” when at least 75% of real visits meet the good threshold for each metric. INP replaced the older FID metric in March 2024. See Google’s official guide to Web Vitals for the definitions.
Field data vs lab data
- Field data comes from real visitors (the Chrome User Experience Report) — this is what Google uses.
- Lab data (such as a Lighthouse test) is a controlled simulation — great for debugging, but not the score Google ranks on.
You will see both in Google PageSpeed Insights. For your own site, also check the Core Web Vitals report in Google Search Console.
How to improve LCP (loading)
- Optimise the hero image: use modern formats such as WebP, the right dimensions and compression.
- Serve from a CDN so files travel a shorter distance.
- Avoid render-blocking code: inline only the CSS you need and defer the rest.
- Use fast hosting and cache pages — static pages are fastest of all.
How to improve INP (responsiveness)
- Ship less JavaScript. Remove unused scripts and heavy third-party widgets.
- Break up long tasks so the browser can respond between them.
- Delay non-essential tools (chat widgets, trackers) until after the page is interactive.
How to improve CLS (stability)
- Set width and height on images and videos so space is reserved.
- Reserve space for ads, banners and embeds.
- Load fonts sensibly to avoid text jumping when the font arrives.
- Avoid inserting content above existing content after the page loads.
Does speed help SEO and sales?
Page experience is one of many ranking signals; relevant, helpful content still matters most. But speed has a direct effect on bounce rate, engagement and conversion — fast pages feel trustworthy, especially on mobile networks. For online stores it influences checkout completion; see our guide on Shopify vs custom e-commerce.
How our websites stay fast
We build with modern frameworks and export sites as static files served from a global network, optimise images to WebP and keep JavaScript lean. If you are choosing a platform, read Next.js vs WordPress.
Speed checklist
- Test your key pages in PageSpeed Insights (mobile first)
- Compress and resize images; use WebP
- Remove unused plugins and scripts
- Add width/height to all images
- Use caching and a CDN
- Re-test monthly in Search Console
Want a faster website?
We can audit your site and fix the biggest speed problems or build a new, lightning-fast one. Ask for a free quote or see our website development service.
