GPSI — Google Page Speed Insights is also a page speed optimizer, but it has fewer frills than WebPageTest and gives less information.
It does not show you all your endpoints individually, but instead gives you an aggregate score for your mobile and web speeds.
Let’s do a quick run through on the popular shoe website Zappos.
First load up https://developers.google.com/speed/pagespeed/insights/ and enter your URL:
Wait for Google to buid your report…
Now you will see the report:
A few things to note:
- GPSI uses several factors and shows you a composite score. You have separate scores for mobile & desktop, so be sure to switch to the “Desktop” tab to see your desktop score.
- Most websites score very low. Rarely do I see a site whose score is above 30, so if yours is low don’t feel bad. Google has very high standards for this tool.
You will see several important metrics. Here is a brief introduction.
Field data is a historical report of how a site has performed and represents “anonymized performance data from users in the real-world on a variety of devices and network conditions.” Lab data, on the other hand, is completely simulated and happens inside of Lighthouse, which is a tool Google is using to analyze your website. (A third metric is Origin Summary which aggregates all pages for the domain.)
First Contentful Paint (FCP) is the average time that it takes the browser to start painting (or rendering) the page. Largest Contentful Paint (LCP) is a measure of loading performance. First Input Delay (FID) is when your web page becomes interactive (known in other tools as “DOM Interactive”).
Read all about the details of GPSI here and be sure to read the details of the web vitals (which explains the meaning of the metrics).