Page speed is a ranking factor, but a weak one. The bigger cost is conversion. Here is what to measure and what usually needs fixing.
Page speed is how quickly a page loads and becomes usable. Google measures it through Core Web Vitals, three metrics covering loading, responsiveness and visual stability. It is a ranking factor, but a weak one. The bigger effect is on conversion, because slow pages lose people before they ever see the offer.
The three numbers Google uses
- Largest Contentful Paint. How long until the main content appears. Aim for under 2.5 seconds.
- Interaction to Next Paint. How quickly the page reacts when someone taps or clicks something. Under 200 milliseconds.
- Cumulative Layout Shift. How much the layout jumps about while the page is still loading. Under 0.1.
Google takes these from real Chrome users, not from a lab test. That matters, because a site can score 95 in Lighthouse on a fast connection and still fail on the field data Google actually uses.
Lab data and field data are not the same thing
PageSpeed Insights shows you both, and people confuse them constantly. The score at the top is a simulated test on a throttled mid-range phone. The section headed “Discover what your real users are experiencing” is 28 days of rolling field data from the Chrome User Experience Report. Only the field data feeds into ranking. Chase those numbers and treat the lab score as a diagnostic.
What usually makes a site slow
Across the sites we audit, four things account for most of it. Oversized images that nobody compressed or converted to WebP. Third party scripts stacking up: chat widgets, heat maps, ad pixels and half-forgotten tag manager containers, all fighting for the main thread. Render blocking CSS and JavaScript sitting in the head. And cheap shared hosting with a slow server response, which caps how fast anything else can possibly be.
Fixing speed is rarely one clever trick. It is a list of unglamorous jobs done in order of impact, and it goes better when someone measures before and after. Our technical SEO service handles this alongside crawl and indexation work.
What good looks like
A well built WordPress site on decent hosting, with caching, compressed images and a tidy script list, will usually land around 1.5 to 2 seconds for Largest Contentful Paint on mobile. That is achievable without rebuilding anything. Getting under one second normally means changing platform or moving to static rendering, and for most businesses the return does not justify the work. Pass the thresholds, then put the time into content.
Related reading: our guides to Core Web Vitals, how to improve Core Web Vitals, using PageSpeed Insights, Largest Contentful Paint and HTTPS.
Common questions
Does page speed really affect rankings?
Yes, but modestly. Core Web Vitals act as a tiebreaker between pages of similar relevance and authority. A fast page with weak content will not outrank a slower page that answers the question better. Treat speed as something to get right, not something to win on.
What is a good PageSpeed Insights score?
90 or above shows green, but the score itself does not feed into rankings. Use it to find problems. The number that counts is whether your Core Web Vitals assessment is marked as passed in the field data section, and in the Core Web Vitals report in Search Console.
Why is my mobile score so much worse than desktop?
The mobile test simulates a mid-range phone on a slow 4G connection, while the desktop test assumes a fast machine on broadband. Mobile is also the version Google indexes. If you only have time to fix one, fix mobile.
How much does a slow site actually cost?
Deloitte’s Milliseconds Make Millions study found that a 0.1 second improvement in load time lifted retail conversion rates by 8.4%. Your own numbers will differ. The reliable pattern is that mobile bounce rate climbs sharply once loading passes about three seconds.
See our glossary entry for page speed for the short version.
