Google PageSpeed Insights is Google's free tool for measuring the speed of a web page, on mobile and desktop. It gives a performance score out of 100, breaks down the Core Web Vitals and lists the fixes to make. At Mazette, we use it to test every page we deliver and spot potential gains before launch.
Why page speed matters for SEO
Speed is one of the page experience signals Google takes into account. Beyond rankings, a slow page drives visitors away: every extra second of waiting increases bounce rate and lowers conversions, especially on mobile.
How to use PageSpeed Insights
- Go to pagespeed.web.dev and paste the URL of the page you want to test.
- Run the analysis and start with the Mobile tab, the one Google prioritises.
- Look at the field data first (your real visitors' experience over 28 days), then the lab diagnostics (a simulated Lighthouse test).
- Scroll down to the Opportunities and Diagnostics sections to get the list of fixes, ranked by estimated savings.
Understanding the score and Core Web Vitals
The performance score reads in three colours: 0 to 49 in red (poor), 50 to 89 in orange (needs improvement), 90 to 100 in green (good). It summarises three key metrics, the Core Web Vitals:
- LCP (Largest Contentful Paint): time to render the largest visible element. Target: under 2.5 seconds.
- INP (Interaction to Next Paint): how quickly the page responds when users click or tap. Target: under 200 milliseconds. INP replaced FID in March 2024.
- CLS (Cumulative Layout Shift): visual stability, meaning elements that move while the page loads. Target: under 0.1.
Our tips to speed up a Webflow site
- Images: convert them to WebP or AVIF directly from the Webflow asset manager, resize them to their real display size and keep lazy loading on below the fold.
- Hero image: set the hero image to "eager" loading to improve LCP.
- Fonts: limit the number of families and weights, and prefer WOFF2 files.
- Third-party scripts: every tracking tool, chat or widget added in custom code weighs on INP. Load them with
defer or after user interaction.
- Animations: keep heavy interactions for the sections that really need them and avoid animating properties that trigger layout recalculations.
- Fixed dimensions: give images, videos and embeds a width and height to avoid shifts that hurt CLS.
Common mistakes to avoid
- Relying only on the desktop score, which is often much better than mobile.
- Testing a single page: CMS templates, blog posts and the homepage each have their own issues.
- Chasing 100/100 at all costs: a score above 90 with green Core Web Vitals is enough in the vast majority of cases.
Frequently asked questions
Is PageSpeed Insights free?
Yes, the tool is completely free and requires no account.
Why does my score change with every test?
The lab test depends on network and server conditions at the time. Variations of a few points are normal, the trend is what matters.
What is the difference between field data and lab data?
Field data comes from your site's real Chrome visitors over 28 days, and it is what Google uses. Lab data is a simulation, useful to diagnose issues and test your fixes.
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