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How to Improve PageSpeed Insights Score

How to improve your website's PageSpeed Insights score from Google Lighthouse

What is PageSpeed Insights?

PageSpeed Insights generates a report on the user experience of a website on both mobile and desktop and provides suggestions to make improvements. If you’ve never heard of the tool, “Google Lighthouse,” it’s a long, automated checklist for your website. After the test, Lighthouse assigns a score for your website to four categories:

  • Performance
  • Accessibility
  • Best Practices
  • SEO 

In short, PageSpeed Insights is simply one way to run a Lighthouse test on your website that shows a combination of both real user data and the test results. In this post, we’ll cover various ways to improve your PageSpeed Insights score.

Example PageSpeed Insights Report: YouTube

A screenshot of the PageSpeed Insights/Google Lighthouse report (YouTube), November 2023
A screenshot of a Lighthouse report (YouTube), November 2023

Next, in this report generated for YouTube.com, you can see they are lacking in the performance and accessibility categories. However, they scored 91 and 92 on best practices and SEO, respectively, which gives them  2/4 green scores.

Example Report: Hailstorm-Development

Hailstorm-Development desktop PageSpeed Insights report
Lighthouse Performance score and metrics for Desktop on PageSpeed Insights, November 2023

For our next example, we used our own website. In this screenshot, you can see our metrics for our website on desktop. We have 3/4 green circles, which is 1 more than YouTube currently has.

Hailstorm-Development mobile PageSpeed Insights report
Lighthouse Performance score and metrics for Mobile on PageSpeed Insights, November 2023

Above, you can see another example of the PageSpeed Insights report for hailstorm-development.com. In this one, you’ll notice the performance score is lower, but the accessibility score is 96 compared to 89 for desktop browsers. Generally, desktop scores are higher than mobile because of load times.

How to Test Your Website with Lighthouse

How to Read Your Report

MetricScore ContributionWhat It Does
Total Blocking Time30%Measures the amount of time that a page is blocked from reacting to user input, like a mouse click
Largest Contentful Paint25%Calculates the time a page takes to load its largest element for users
Cumulative Layout Shift25%Measures the layout shifts that occur as users access a page
First Contentful Paint10%Measures the time at which first text or image becomes visible to users
Speed Index10%Shows how quickly the content of a page is loaded

Next, you must know what each score measures and how it affects your website’s overall scoring. This should help you to prioritize which features to try to improve first. If you want to see a more detailed breakdown of your score, simply click on “See Calculator” and it will show you a detailed calculation like this:

Example of Lighthouse Scoring Calculator which includes the latest v10 updates for FCP, SI, LCP, TBT, and CLS
Example of Lighthouse Scoring Calculator which includes the latest v10 updates for FCP, SI, LCP, TBT, and CLS

How to View Lighthouse Recommendations

Once your report has finished generating, all you have to do is scroll down and click on the various metrics to load suggestions and estimated savings.

In this screenshot, you can see that the first opportunity is to eliminate render-blocking resources. There is a link as well that includes a how-to document regarding these changes. Lastly, you can see the transfer size and estimated potential savings in the third column. 

Going through each of these suggestions could highlight how many small adjustments can be made for a score boost. 

A screenshot of opportunities outlined by Google Lighthouse (PageSpeed Insights Report); example: eliminate render-blocking resources by delivering JS/CSS inline and deferring all non-critical JS/styles.
A screenshot of opportunities outlined by Google Lighthouse (PageSpeed Insights Report); example: eliminate render-blocking resources by delivering JS/CSS inline and deferring all non-critical JS/styles.

In Conclusion

Ultimately, it may be difficult to increase your score in Google Lighthouse, but investing in it will pay off in many ways. Not only will you be able to determine what changes need to be made to improve accessibility, but also identify other areas to improve like reducing unused CSS and JavaScript. What do you think about PageSpeed Insights? Let us know in the comments below.

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