How fast should your website be? Core Web Vitals in plain language

A slow website loses visitors before they have read anything. Google measures that speed with three figures, the Core Web Vitals, and takes them into account in the search results. What do they mean, and what is good enough?

Why speed matters

Someone looking something up on their phone does not wait. If the page stays white or everything jumps around while they want to click, they go back to the search results and click on the next one. So speed is not about technology, but about customers who stay or leave.

The three figures

• How quickly do you see something? (LCP) The time until the largest element on the page, usually the main photo or the title, is visible. Good is 2.5 seconds or less.
• How quickly does the page respond? (INP) The time between a tap or click and the moment something visibly happens. Good is 200 milliseconds or less.
• Does everything stay in place? (CLS) Does the page jump while it loads, so that you tap next to the button? This is expressed as a score, and good is 0.1 or less.

Google assesses those figures on the basis of real visits, mainly on mobile. So a site that feels smooth on your fast office computer can still score poorly on a phone with a weak connection.

Measuring it yourself

You can do that for free with Google's PageSpeed Insights: you enter the address of your page and get the three figures, for mobile and for desktop. In Google Search Console you can see under "Core Web Vitals" how your whole site is doing with real visitors.

Do not test only your homepage. Also test the page your customers arrive on and the page where they have to do something, such as a product page or a form.

What makes a site slow

• Images that are too heavy. A photo straight from the camera is often ten times larger than necessary.
• Too many scripts. Every chat button, tracker and plug-in loads its own code, even on pages where it does nothing.
• Fonts and videos that hold everything up. The text is already there, but only appears once the rest has loaded.
• Slow hosting. If the server takes a long time to think, the rest no longer helps.
• Images without fixed dimensions. They make the page jump when they come in.

Speed is something you build in

Speeding a site up afterwards only works up to a point: a site made up of many separate parts keeps loading all those parts. The biggest gain lies in how a site is built. That is why our custom websites load only what a page needs, images are delivered automatically in the right format and every image gets its fixed place, so that nothing jumps.

Speed is not a goal in itself either. A fast page that does not say what you do achieves nothing. But a clear page that loads too slowly is never read.