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Google recently released Lighthouse 10, the latest version of its open-source tool for analyzing and optimizing web pages.
There are several significant changes and improvements that web developers and site owners need to know about.
Read on.
One of the most significant changes in Lighthouse 10 is the removal of Time to Interactive (TTI).
The depreciation process started in Lighthouse 8, and Lighthouse 10 marks its conclusion.
TTI's score weight, which was 10%, is now being transferred to Cumulative Layout Shift (CLS), increasing its overall performance score weight to 25%.
The reasoning behind Google’s decision was:
Put simply:
There are better and more reliable metrics to measure the time it takes for a page to become fully interactive after a user arrives on it.
Also, Google once again shows that the future belongs to the field metrics.
The good news is that most site owners will see an improvement in their Lighthouse performance scores.
Out of the 13 million page loads analyzed in the most recent HTTP Archive run, around 90% of them are expected to experience an increase in their Lighthouse performance score. Approximately 50% of these pages will see a performance boost of over 5 points.
As it turns out, most sites score better for CLS than TTI.
In case you’re experiencing CLS issues and low scores, the following techniques could help:
You can find more in-depth information and best practices in our CLS guide.
Lighthouse 10 introduced a brand new performance audit and an update to an existing one.
The back/forward cache (bfcache) is a highly effective tool for enhancing the performance of a web page for actual users. Unlike the standard browser cache, a page that is loaded from the bfcache can quickly restore the page layout and execution state, bypassing most of the page load activity.
This makes the page immediately accessible to users as they navigate back and forth through their browsing history.
The great thing about bfcache is that you don’t have to do anything to set it up. Browsers do it automatically.
However, in some cases, a page can prevent the browser from restoring a page from the bfcache. When that happens, Lighthouse’s newest audit will fail:
But the good news is that it will list the reasons for failure, so you will know exactly what to optimize.
The previous Best Practices audit, "Allows users to paste into password fields," has undergone an expansion to verify that pasting is feasible for all input fields except for read-only ones. For many websites, disabling the paste function creates a negative user experience and hinders necessary safety and accessibility workflows.
The new audit is now "Allows users to paste into input fields" (paste-preventing-inputs).
Lighthouse 10 is available on the command line through npm and in Chrome Canary. It will also soon be available in PageSpeed Insights and Chrome stable in Chrome 112, currently scheduled for release on March 29, 2023.
Niko has 5+ years of experience turning those “it’s too technical for me” topics into “I can’t believe I get it” content pieces. He specializes in dissecting nuanced topics like Core Web Vitals, web performance metrics, and site speed optimization techniques. When he’s taking a breather from researching his next content piece, you’ll find him deep into the latest performance news.