PageSpeed Insights (PSI)
PageSpeed Insights (PSI) is Google's free tool that scores a web page's performance from 0 to 100 and reports its Core Web Vitals. It combines lab data, measured by Lighthouse in a controlled test, with real-world field data from Chrome users.
In practice
You give PSI a URL and it returns a mobile and a desktop performance score out of 100, the page's Core Web Vitals, and a list of specific opportunities, render-blocking scripts, oversized images, and the like. The score is a weighted blend of lab metrics like First Contentful Paint, Speed Index, and Largest Contentful Paint, computed by the open-source Lighthouse engine [2].
Google groups the score into three bands: 90 to 100 is good, 50 to 89 needs improvement, and below 50 is poor [1]. Scoring is mobile-first, which matters because a site can feel fine on your desktop and still score in the 50s on the phone most buyers actually use.
For a B2B company it is the free, credible speed check, and worth running. Load time affects whether a first-time visitor stays, and Core Web Vitals are a Google ranking signal, so a slow homepage costs you on both conversion and search. PSI is also the number a prospect or competitor can pull on your site in ten seconds, so it is worth knowing yours.
Its limit is context, not accuracy. PSI hands you a score with no benchmark and no priority order: it tells you what is slow, not how you compare to the companies winning your buyers, or which single fix matters most for your site. That gap between a raw reading and a diagnosis is exactly why a website audit that interprets the score is more useful than the score alone.
A test worth doing right now: run your homepage through PageSpeed Insights on the mobile tab, note which band your score lands in, and read the top opportunity it lists. If your score sits in the 50s, you are roughly average for B2B, and average is slow enough to lose buyers.
Common questions
What is a good PageSpeed Insights score?
90 or above is Google's “good” band, 50 to 89 needs improvement, and below 50 is poor. Most B2B sites land in the 50s to 60s. Aim for the good band on mobile, but treat the score as a proxy, the underlying Core Web Vitals and load time are what actually affect buyers.
What's the difference between PageSpeed Insights and Lighthouse?
Lighthouse is the open-source engine that runs the controlled lab test and produces the score. PageSpeed Insights is Google's hosted tool that runs Lighthouse for the lab data and adds real-world field data from Chrome users. Lighthouse is the engine; PSI is the product built around it.
Does the PageSpeed score affect Google rankings?
Indirectly. The performance score itself isn't a ranking factor, but the Core Web Vitals it reports are part of Google's page experience signals. A page that scores poorly usually has weak Core Web Vitals, which can hold back rankings alongside slower conversion.
Why does my PageSpeed score change every time I run it?
The lab test runs on a simulated device and network, so small variations are normal between runs. The field data is a rolling 28-day average of real Chrome users and moves more slowly. For a stable read, run it a few times and look at the field data.
Sources
- Google, “About PageSpeed Insights.” developers.google.com/speed/docs/insights/v5/about
- Chrome for Developers, “Lighthouse performance scoring.” developer.chrome.com/docs/lighthouse/performance/performance-scoring