What if we hit the gas! Today, users leave your site if it doesn't load after 3 seconds. With PageSpeed Insights, you can identify what slows your site down and go to the next gear.


What is PageSpeed Insights?

PageSpeed Insights API (PSI) is a free app offered by Google to measure a page's performance, on mobile, tablet and computer. The data collected is accompanied by advice on how to improve the page.
These improvements can help reduce page loading times, but also bounce rates. Both factors are crucial for the SEO of your site.


How to interpret the data calculated by PageSpeed Insights ?

When you analyze a URL, you get a detailed report within seconds that takes into account two parameters:
- The FCP: time it takes the page to be displayed for the user.
- The FID : time it takes for the page to be fully loaded (of the DOM). This corresponds to the time it takes the browser to completely load the page. It indicates the time elapsed between the moment the user interacts with an element of your page and the moment the browser is ready to respond to his request.
Page Speed Insights retrieves the URL twice: the first time with its desktop user agent (=its robot for desktop rankings) and the second time with its mobile user agent.


The scores being displayed go from 0 to 100 points. Don't worry, if your site is not at 100% everywhere, it's normal! Few sites manage to do so because the criteria are so strict. But you should try to get as high a score as possible.
If you see a lot of red and yellow in your report, it means that your site is experiencing significant problems during page loading.

How to improve your score on Page Speed Insights?

To improve your score, you "simply" have to follow the app's recommendations. These are sometimes quite technical, we will demystify with you the main recommendations encountered.

Avoid landing page redirects

The use of 301 redirects is sometimes unavoidable, but they should be limited as much as possible.
Indeed, each time a user is redirected, you lose precious seconds. This case is quite common on sites with a mobile version. Each page is redirected to its mobile version. This is why Google recommends responsive design for mobile.

Enable gzip compression

Browsers like Chrome and Firefox are able to offer a reduced version of a page. By enabling gzip compression, these pages can be shrunk by 90%. Thus, instead of serving the user the whole page, the browser directly retrieves the compressed version on small screens.

Minimize CSS, HTML and JavaScript

Minifying code means removing unnecessary or repetitive data without altering its loading and display of the page on the browser. Bad coding is often the cause of this problem, but don't panic, there are solutions to minify your code, without starting from scratch:
- The HTML minifier to minify HTML
- CSSNano and csso.
- UglifyJS2 and the closing compiler to minify JavaScript
Another option is to use the AMP format to offer search engines a simplified version of your pages that will load in a few milliseconds and will be kept in the Google cache.

Optimize and reduce images weight

Images can represent a large part of a page's total weight. They are everywhere: from your logo to your sliders. They must therefore be optimized as much as possible to reduce their impact on loading time. This is the least complex technical optimization. Simply convert them to JPEG and compress them as much as possible (taking care not to alter their quality). There are compression tools like Compressor, ezGIF, TinyJPG...

Reduce the use of JavaScript

Javascript must be used sparingly because it makes the code considerably heavier. Synchronous scripts prevent parallel loading and sometimes block the display of the page. Scripts must therefore be relayed to the background by placing them at the bottom of the source code. They will be retrieved and executed only after the page is displayed.

Speed up the server's response time

The server plays an important role in the loading time of a page. It can be slowed down by several factors such as the number of requests called, slow routing, insufficient memory, etc. If Page Speed Insights indicates that your server is slow, you should contact your hosting solution. It is sometimes tempting to give in to the appeal of low prices by choosing a shared package, but depending on the type of site, it is preferable to opt for a dedicated server, which will show better performance.

PageSpeed Insights update

Recently, Page Speed Insights has undergone a major update of its functionalities. Until now, Google relied on several performance tools to evaluate the performance of sites, which produced varied recommendations, not always easy to understand. That's why Google has unified the data from its tools so that webmasters get the same results everywhere. From now on, Page Speed Insights is powered by Lighthouse which is an open-source automated tool to improve the quality of web pages. It is accessible from Chrome DevTools, a command line or as a Node module.
So this change brought big changes to Page Speed Insights, which now distinguishes between lab data and "field" data. Lab data is for debugging purposes because it is from a controlled environment. Field data captures the actual user experience, especially on mobile. Lighthouse emulates a 3G network to simulate the load time on a standard mobile network. It is this element in particular that is a real revolution!


PageSpeed Insights is an excellent tool to measure the performance of pages, and since its update, it offers much more reliable data for loading times on mobile. However, it remains insufficient as a pure analysis tool. It does not integrate mobile compatibility data or possible blocking factors (noindex tag, bad canonical URLs, etc.). It is therefore essential to cross reference it with several other analyses to get a precise idea of the real performance of a page.

   Article written by Louis Chevant

Further reading

The complete guide to using the Google Search Console

Google Search Console: free tool provided by Google to analyze the SEO performance of your website.