A slow website loses customers quietly. Nobody rings to complain. They just tap back and choose the next result. Core Web Vitals are Google’s way of measuring how a page feels to use, and you can understand them without any technical background.
The short version
| Measure | What it means in plain English | Good score |
|---|---|---|
| Largest Contentful Paint (LCP) | How long until the main content appears | Within 2.5 seconds1 |
| Interaction to Next Paint (INP) | How quickly the page reacts when you tap | 200 milliseconds or less1 |
| Cumulative Layout Shift (CLS) | Whether things jump around as it loads | 0.1 or less1 |
What each one means
Largest Contentful Paint measures loading performance. Think of it as the moment you can see the thing you came for, usually a large image or heading. A good page gets there within 2.5 seconds of starting to load.1
Interaction to Next Paint measures responsiveness. If you tap “menu” and nothing seems to happen for a moment, you may tap again. That sluggish feeling is what this measures, and pages should respond in 200 milliseconds or less.1
Cumulative Layout Shift measures visual stability. You have probably tried to tap a button, only for an image to load above it so that you tap the wrong thing. Pages should score 0.1 or less.1
Measure real visitors, not your own laptop
Your site probably feels fast to you, because you have a fast computer and your browser has already saved parts of it. Your customers may be on an older phone with a poor signal in a car park.
That is why web.dev recommends measuring the 75th percentile of page loads, split between mobile and desktop. A page passes if it meets the targets at that level for all three measures.1
In plain terms, three out of four visits should have a good experience. A few fast visits do not make up for a slow experience for everyone else.
Does this affect your Google ranking?
Google says that Core Web Vitals, along with other page experience aspects, align with what its core ranking systems seek to reward.2 Good scores help, but they do not replace useful content, and a fast page saying nothing useful will not rank.
The stronger argument is simple: a faster site is nicer to use, which is good for your business whatever Google does.
How to check your own site
These tools are free:
- Google Search Console reports on your real visitors, once your site has enough traffic.
- PageSpeed Insights gives you real-visitor data where available, plus a lab test of any page.
A small site may not have enough visitors for real-user data. If so, the lab test is still a useful guide, but it remains an estimate.
Test on your phone as well. Open your site on mobile data, not your home wifi, and see how it feels. It is the most honest test there is.
What usually slows small business sites down
These are the problems we look for first, based on how these measures work:
- Huge images. A photo straight from a phone can be many times larger than it needs to be. Resize and compress them, and use modern formats.
- Too many plugins and scripts. Each chat widget, tracker and slider adds code that the phone must process before the page can respond.
- Web fonts loaded poorly. These can delay text, or make it jump when they arrive.
- Images with no set size. The browser does not know how much room to leave, so everything moves once they load.
- Pop-ups and banners that push content down, which is a common cause of layout shift.
- Slow hosting. A cheap server can make every page start late.
- Pages built entirely in the browser. If the phone has to run a lot of code before it can show anything, older phones will suffer. Search engines also have to queue such pages for an extra rendering step.3
What good looks like in practice
When we build a site, we set limits on how much code and how many images each page may load, and check them on every update. We keep content in the page’s first response, reserve space for images and fonts, and avoid third-party scripts where we can.
These are our working rules, and they keep the site fast as it grows. Speed tends to slip over time unless something checks it, because each small addition seems harmless by itself.
Where to go next
If your site feels slow, start with images, because that is usually the biggest and cheapest win. Then remove any script you do not truly need.
If you would like a site built with these limits from the start, see our website design service, and try the sample trades website on your own phone. For the bigger picture on being found, read SEO basics for a small business website.
Sources
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web.dev, Web Vitals, accessed 7 November 2026. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7
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Google, Understanding Core Web Vitals and Google search results, accessed 7 November 2026. ↩
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Google, Understand JavaScript SEO basics, accessed 7 November 2026. ↩
Websites that bring in enquiries
A fast site that works on the phone in your customer’s hand, says clearly what you do, and makes it easy to get in touch.
See how it works