WordPress glossary
CLS (Cumulative Layout Shift)
How much the page jumps around as it loads. Pass under 0.1. Often caused by ads, web fonts, or images without dimensions. Fixed by reserving space.
Last updated ยท Reviewed by Ali Yasin Jatoi
CLS is caused by images without width and height attributes, ads injected late, and web fonts swapping in. Set explicit dimensions on every image and reserve space for embeds to fix most CLS issues.