In this article · 7 sections
Paste your website into Google's PageSpeed Insights and you get a score out of 100, coloured red, orange or green, and a long list of recommendations. It's useful, but often misunderstood. Here's how to read it properly.
Two kinds of data
Field data (real users)
At the top, under "Discover what your real users are experiencing", you may see Core Web Vitals assessment: Passed or Failed. This comes from real Chrome users visiting your site over the previous 28 days (the Chrome UX Report).
- This is what Google uses as a ranking signal for page experience
- New or low-traffic sites may show "No data" because there aren't enough visits
Lab data (a simulated test)
Below that is the performance score from a Lighthouse test run on a simulated mid-range phone with a throttled connection. It's a single test under fixed conditions.
- Great for diagnosing problems
- Scores can vary between runs
- The number itself isn't a ranking factor; the real-user experience is
Key point: a lab score of 65 with field data "Passed" is generally fine. A lab score of 95 with field data "Failed" means real users are struggling.
The metrics
Core Web Vitals
- LCP (Largest Contentful Paint): how fast the main content (often the hero image or headline) appears. Good: 2.5 seconds or less
- INP (Interaction to Next Paint): how quickly the page responds when users tap or click. Good: 200 ms or less
- CLS (Cumulative Layout Shift): how much the layout jumps while loading. Good: 0.1 or less
See Core Web Vitals explained.
Other useful metrics
- FCP (First Contentful Paint): when something first appears
- TTFB (Time to First Byte): how fast the server responds (shown in field data)
- TBT (Total Blocking Time): lab metric related to heavy JavaScript
Reading the recommendations
Recommendations are grouped under Diagnostics and Opportunities, with estimated savings. Prioritise by impact:
- Slow server response / TTFB: check hosting, caching and database. See browser and server caching
- LCP element issues: a heavy or lazy-loaded hero image. See lazy loading done right
- Properly size and compress images
- Reduce unused JavaScript / third-party code. See third-party scripts
- Render-blocking resources: CSS and fonts loaded in the head
- Layout shift culprits: images without dimensions, late banners, fonts
Ignore the urge to chase every small item. A few big fixes usually deliver most of the gain.
Mobile vs desktop
Always look at mobile first. Google uses mobile-first indexing, and most Indian visitors are on phones. Desktop scores are typically much higher.
Test the right pages
Don't just test the homepage. Test your top landing pages: main service pages, top blog posts, product pages. Search Console's Core Web Vitals report groups similar pages, showing which templates need work.
How often to check
- After any design change, new plugin or new script
- Monthly as part of maintenance. See website AMC
Remember: field data takes about four weeks to fully reflect improvements.
Keep perspective
Speed matters for users and conversions, and it's part of Google's page experience signals, but content relevance still matters most for rankings. Aim for "good" Core Web Vitals, not a perfect 100.
We include speed checks and fixes in our maintenance plans. Ask for a speed review.