When is a site slow?
Google measures page speed with three numbers, the Core Web Vitals. A page is good if it stays under these limits for 75 per cent of visits:1
| Metric | What it tells you | Good |
|---|---|---|
| LCP | How quickly the largest element, often the main photo, is on screen | 2.5 s or faster |
| INP | How quickly the page responds when you tap something | 200 ms or faster |
| CLS | How much the page shifts while loading | 0.1 or less |
Google uses the Core Web Vitals in its ranking, but relevance comes first: a slow page with the best answer can still rank at the top.2 Speed matters most for your visitor, who will not wait on a phone on the go.
What makes a site slow
These are the usual suspects, with the biggest gain at the top.
Large photos
A photo straight from the camera is often several megabytes. WebP photos are 25 to 34 per cent smaller than comparable JPEGs.3
Typical when: there is a large image at the top of every page.
One size for everything
A phone gets the same large photo as a big screen. That wastes data, especially on a slow connection.4
Typical when: the site does not offer different sizes per screen.
Wrong lazy loading
Photos further down may load later, but the main photo at the top should not.5
Typical when: a plugin defers all photos by default.
Too much JavaScript
Downloading and running scripts takes the most time on a phone. According to Google's V8 team, it is wise to split up large bundles.6
Typical when: there are many plugins, sliders, chat widgets and trackers.
Shifting page
Ads, cookie banners or photos without fixed dimensions push the content away while you read.
Typical when: elements only take their place after loading.
Measure it yourself
- Open Google's PageSpeed Insights and enter your address. Look at the Mobile tab.
- Look at LCP first. If it is above 2.5 seconds, start with the main photo.
- Check the Core Web Vitals report in Search Console. It is based on real visitors.
- Run the free website check. It measures speed on a simulated mobile connection.
How Ekkora handles it
Speed is one of the eight checks before launch, measured with Lighthouse on a simulated mobile connection. For sites with 3D, we measure with the 3D object on the page, not without it. Read more in a website with 3D.
Questions
- My site is fast on my laptop. Why do customers complain?
- A laptop on wifi is much faster than a phone on 4G. So always test on mobile, or with PageSpeed Insights on the Mobile tab.
- Does better hosting help?
- Sometimes. If the server responds slowly, you can see it right at the start of loading. But usually the gain is in photos and scripts, not in the server.
- Do I need a score of 100?
- No. What matters more is that your real visitors stay under the Core Web Vitals limits. A score is a snapshot in a test.