Visitors don't wait: if a page loads slowly, they move on, and Google ranks it lower too. Here's how to measure your site's speed in five minutes, what usually lies behind a slow site, and which fixes help most.
How do you measure it in 5 minutes?
Open Google PageSpeed Insights, enter your address and look at the mobile result. The top part shows real-visitor data (if there's enough traffic); the bottom part is a lab test with concrete suggestions. The Core Web Vitals report in Search Console shows which pages are slow across the whole site.
The three metrics and their thresholds
- LCP (main content appears): good if under 2.5 seconds.
- INP (response to a click): good if under 200 milliseconds.
- CLS (layout shift while loading): good if under 0.1.
What makes a site slow?
- Images: multi-megabyte photos that the browser downloads at full size even on phones.
- Third-party code: chat widgets, several analytics tags, ad pixels, embedded videos and maps.
- Plugins: a WordPress site built up over years often runs a dozen plugins stacked on top of each other.
- Hosting and caching: cheap, overloaded servers without caching or a CDN.
- Fonts: many font variants loaded from an external server.
What helps most?
- Optimise images: modern formats (WebP, AVIF), sizes that fit the screen, lazy loading. Often this alone brings the biggest improvement.
- Clean up third-party code: remove what you don't need; load the rest later or only after consent.
- Caching and CDN: serve the page pre-built from a server close to the visitor.
- Plugins and theme: remove unnecessary plugins, replace a slow theme.
- Rebuild: if the foundations are outdated, a site built on modern technology (e.g. Next.js and a headless CMS) can be cheaper than endless patching.
When should you call in an expert?
When PageSpeed stays red on mobile, when Search Console flags many pages as slow, or when fixing one thing breaks another. An audit shows which step brings the most for the least work; see What does a system audit cover?
Updated: 12 November 2026
