Google has announced the release of Lighthouse 8.0 for the end of August in Chrome. This new version should paradoxically offer a mix of scoring that is both stricter and at the same time less severe in some aspects. But it is already estimated that most sites will benefit from increased scores.
Google Lighthouse 8.0
As a reminder, Google Lighthouse is developed by Google and aims to help web developers. It is an automated open source tool that helps publishers, developers and SEO specialists measure website page speed and other metrics related to web page performance, accessibility and SEO. Lighthouse powers the online PageSpeed Insights tool and is also provided as a developer tool in Chrome.
Lighthouse also includes the ability to test progressive web applications for compliance with current standards and recommended best practices.
The new version 8.0 of Lighthouse will be available soon in Chrome 93, but it can be used now in PageSpeed Insights.
Google PageSpeed is a tool that analyzes the performance of your web pages, generating a report on the overall speed of your site, and providing practical advice on how you can improve its score. PageSpeed Insights only measures performance indicators, while Lighthouse can audit other aspects of your website (SEO, accessibility, progressive web application, etc.)
The changes that will happen with Google Lighthouse 8.0
So, Google has updated Lighthouse 8.0 and one of the important changes seen in the new version is the change in the values of different speed metrics. It is believed that the changes will make it easier for most sites to achieve higher web page speed scores. CLS, or Cumulative Layout Shift, scores should tend to increase while other performance indicators should become stricter.
Here are the changes to the Google Lighthouse tool:
The performance score has been reweighted.
The Total Blocking Time (TBT) score is getting stricter (Total Blocking Time is a metric that measures the total time a page is blocked from responding to user input, such as mouse clicks or presses on your keyboard).
The First Contentful Paint (FCP) score is also getting stricter (First Contentful Paint, abbreviated to FCP, measures the time from when navigation begins until the browser displays the first content on the screen).
The Cumulative Layout Shift (CLS) score, as mentioned earlier, becomes less strict (The Cumulative Layout Shift is a performance indicator that measures the instability of content. It is obtained by adding up the layout changes that occur beyond the first 500 milliseconds of a web page’s load).
How do these changes affect scores?
According to the evidence available in Google’s FAQ section, about 20% of websites will see a drop in score, which could be as much as five points lower, while 20% of sites could see virtually no change.
Google also estimates that about 60% of sites will see a positive change, which could result in a score improvement of 5 points or more.
Overall, it is estimated that there are more winners with this new version of Lighthouse 8.0 that will get a higher score than sites that will see a drop in score.
Here are the details of the estimates made by Google about the expected changes:
About 20% of sites are expected to see a drop in score of up to 5 points
About 20% of sites will detect very little change
About 30% of sites should see a moderate improvement of a few points
About 30% of sites may see a significant improvement of 5 points or more
Google adds that the most significant score decreases are due to the TBT (Total Blocking Time) criterion which becomes stricter and whose coefficient on the final score takes more weight, and that, paradoxically, the score improvements are also due to the TBT changes in the long tail and CLS windowing, and the higher weights of these two indicators.
Stricter score at the level of total blocking time (TBT)
As explained above, TBT measures the time it takes for a web page to respond to scrolling, mouse movements, or keystrokes on your keyboard. The goal is to have a low TBT score that corresponds to a page that is almost immediately interactive.
The recently updated total blocking time score is described as more stringent.
According to information provided by Google, the scoring criteria could have been even stricter. But the engineers in charge of the Lighthouse 8.0 project for the American search engine finally decided not to implement these criteria in order not to “shake up” internet professionals too much.
Scores before and after the new Lighthouse 8.0 version
Google has released a Lighthouse score calculator that shows the differences between versions 8.0, 6 and 7, and version 5.
This allows to see the differences between the different versions and to compare the scores.
The detailed results can be seen here: https://googlechrome.github.io/lighthouse/scorecalc/
Update of the Lighthouse API
Google has published a note on the changes to the API:
“The new Cumulative Layout Shift definition is now represented by the default metric presented as “cumulative_layout_shift”, the previous Cumulative Layout Shift metric will be available for a limited time as it is phased out as “experimental_uncapped_cumulative_layout_shift”.
Largest Contentful Paint has undergone adjustments in recent versions of Chrome and has been similarly updated in CrUX.
The first Contentful Paint tri-binning thresholds have been updated as follows: [0-1.8s], (1.8s-3s), [3s – ∞].
Discover your new page speed scores
If you want to find out your new page speed scores, just go to the PageSpeed Insights page: https://developers.google.com/speed/pagespeed/insights/