This tool from an ex-Google engineer…
This tool from an ex-Google engineer checks and visualizes the Cumulative Layout Shift of any website.
Cumulative Layout Shift is a “Core Web Vital” metric that measures “the instability of content by summing shift scores across layout shifts that don’t occur within 500ms of user input. ”
“Have you ever visited a website and was about to click a link to an article, and thenβ¦ the layout suddenly moves, an ad appears, and somehow instead of clicking on the article you wanted to read, you click on the useless ad?”