PageSpeed Insights (PSI) scores have recently improved across the board. But the improvements have nothing to do with any changes made to the websites experiencing better scores. The improvements happened over on Google’s side.
PageSpeed Insights
PageSpeed Insights is a Google tool that provides reports on a website speed performance. The tool provides both mobile and desktop page speed reports along with actionable insights about different problems that were discovered.
PSI provides two kinds of reporting, lab data and field data.
Lab Data
Lab data is a report generated using simulated devices and Internet speeds. The purpose of testing a site using simulated environments is to provide insights into issues that may cause a slower user experience.
Lab data can note code-level factors that can cause the user experience to degrade and suggests ways to fix those problems.
The lab data is a way to audit a web page and identify areas that need improving.
Field Data
Field data is information gathered through actual users browsing the site with Chrome and archived in the Chrome User Experience Report (CrUX).
Field data is useful for understanding what kind of performance site visitors are actually experiencing on the site under real-world environments.
The Core Web Vitals scores come from the field data archived in CrUX.
These metrics consist of Largest Contentful Paint, First Input Delay and Cumulative Layout Shift.
The field data that is reported in the PageSpeed Insights tool is from a previous 28 day cycle. Recent changes to the website may not be reported in the field data portion of the report.
That’s why targeted improvements to a website will not be reflected in the field data, particularly the Core Web Vitals scores, until the next 28 day cycle is reported on.
Google Updated How PageSpeed Insights Gathers Data
Google announced an important change in how the PageSpeed Insights tools gathers information. The change is a switch to using the http/2 protocol for connecting to a web page.
PageSpeed Insights Using HTTP/2
HTTP/2 is an advanced network connection protocol that allows faster transmission of data. Under the previous HTTP/1.x protocol there were limits to how much data could be transmitted, which led to various workarounds.
The HTTP/2 protocol does not have those limitations.
According to an HTTP/2 explainer published by Google:
“HTTP/2 modifies how the data is formatted (framed) and transported between the client and server, both of which manage the entire process, and hides all the complexity from our applications within the new framing layer.
As a result, all existing applications can be delivered without modification.”
HTTP/2 allows faster transfer of data. That in turn improved the PageSpeed Insights scores across all metrics. The only hangup is if your server does not support HTTP/2.
It’s highly likely your server supports HTTP/2. If the server hosting your site does not support HTTP/2 you may want to consider calling your web host customer support and finding out how to activate it.
There are many tools that test websites for HTTP/2 compatibility. Google’s Lighthouse tool goes further by reporting if third party resources loaded by a site that do not support HTTP/2.
HTTP/2 provides a performance boost for clients (browsers and crawlers) that support HTTP/2.
That performance boost is why the PageSpeed Insights scores are going up across the board, because the PSI data is now gathered using the new faster protocol.
Google’s PageSpeed Insights Update Announcement
According to Google’s announcement:
“As of March 3, 2021, PageSpeed Insights uses http/2 to make network requests, if the server supports it.
…With this change, network connections are often established quicker. Given your requests are served in h2, you can likely expect metrics and the performance score to improve.
In general, performance scores across all PageSpeed Insights runs went up by a few points.”
PageSpeed Insights Scores are Now Higher
If you have been pleasantly surprised to see better PageSpeed Insights scores beginning March 3rd, this is the reason why. So don’t get a big head about it.
Official Announcement of PSI Now Using HTTP/2
Chrome User Experience Report (CrUX)
