Note from 14 October 2022

width and height attributes on <img> help prevent layout shifts (CLS). Values should be unitless integers.

But #Lighthouse sees 100% as 100, thanks parseInt()

Do you think it should be improved?


  1. screenshot of What's new in Lighthouse 10

    Brendan Kenny avatar Brendan Kenny

    What's new in Lighthouse 10

    The venerable Time To Interactive (TTI) metric is being removed in Lighthouse 10, with its 10% score weight shifted to Cumulative Layout Shift (CLS), which will now account for 25% of the overall performance score. Ideally this change will increase focus on CLS for sites that still need fixes for unnecessary layout shifts.

  2. I have a client site with a header that is hidden when the user scrolls down, but shown again when the user scrolls up, which seems pretty comon nowadays.

    This triggers some CLS, even if the hide/show is done in less than 500 ms, as “continuous interactions such as scrolls, drags, or pinch and zoom gestures are not considered ‘recent input’”. 😞

  3. Same page tested on PageSpeed Insights over a few hours the same day, without anything modified, and the desktop scores vary from 19 to 59… 🤷‍♂️

    A lot of businesses rely on this crap to now if their site is "fast" enough for Google SEO! 😭

    Three different scores: 44, 59, 19