What this website speed test measures
We load the page from our server and break the time down into each step a browser goes through before it can start rendering: resolving the domain name (DNS), opening a TCP connection, negotiating TLS encryption, waiting for the server to generate the page (time to first byte) and downloading the HTML. Then we analyse the HTML for the things that most often slow pages down in the browser.
Core Web Vitals in brief
| Metric | Measures | Good |
|---|---|---|
| LCP (Largest Contentful Paint) | When the main content appears | ≤ 2.5 s |
| INP (Interaction to Next Paint) | How quickly the page reacts to clicks and taps | ≤ 200 ms |
| CLS (Cumulative Layout Shift) | How much the layout jumps while loading | ≤ 0.1 |
| TTFB (Time to First Byte) | Server and network responsiveness | ≤ 0.8 s |
A slow server response delays everything else, which is why TTFB is the first number to optimise. Render-blocking scripts and stylesheets delay LCP, images without dimensions cause CLS, and heavy JavaScript hurts INP.
The most effective speed fixes
- Cache pages and use a CDN so most visitors get a ready-made page from a nearby server.
- Enable brotli or gzip compression for HTML, CSS and JavaScript.
- Defer non-critical JavaScript with
deferorasync, and remove unused tags and plugins. - Optimise images: serve WebP/AVIF at the displayed size, set width and height, and lazy-load below-the-fold images.
- Enable HTTP/2 and HTTP/3 and preconnect to essential third-party origins.
- Avoid redirect chains; check them with the redirect checker.
Looking for your own connection speed instead? Use our internet speed test. For search visibility, run the SEO checker.
Frequently asked questions
Why are my results different from PageSpeed Insights or GTmetrix?
Each tool tests from different locations, devices and network speeds. Lab tools simulate a mid-range phone on a slow network; this test measures server-side timings from our data centre. Track changes over time with the same tool.
Does this test load images and scripts?
No. It downloads and analyses the HTML document. Resource counts and recommendations come from the HTML, which keeps the test fast and gentle on the site.