Largest layout shift score on React sites

Sites with a largest shift under 0.01 largest single layout shift score have a good CLS most often: 94%, against 92% of all React sites. Sites with a largest shift over 0.25 largest shift have it least often, at 65%.

A largest shift under 0.01 is the most used: 36.7% of React sites.

Wix sets the largest single layout shift score to a largest shift under 0.01 on 52% of its sites, and 98% of Wix sites have a good CLS, against 92% of all sites.

PlatformLargest single layout shift score on its sitesGood CLS

React sites with largest single layout shift score 4,093 sitesUnder 0.01 (Imperceptible) 37%0.01 to 0.10 (Within Good budget) 37%Over 0.25 (Poor in one jump) 15%0.10 to 0.25 (Needs Improvement) 12%92%

Wix 1,223 sitesUnder 0.01 (Imperceptible) 52%0.01 to 0.10 (Within Good budget) 34%98%

WordPress 1,784 sites0.01 to 0.10 (Within Good budget) 37%Under 0.01 (Imperceptible) 35%0.10 to 0.25 (Needs Improvement) 14%Over 0.25 (Poor in one jump) 14%85%

Under 0.01 (Imperceptible) 0.01 to 0.10 (Within Good budget) Over 0.25 (Poor in one jump) 0.10 to 0.25 (Needs Improvement)

Does the platform explain the largest single layout shift score difference?

On WordPress, 93% of sites with a largest shift under 0.01 largest single layout shift score have a good CLS, against 91% of WordPress sites with a largest shift of 0.01 to 0.10. Within WordPress, sites with a largest shift under 0.01 and a largest shift of 0.01 to 0.10 have a good CLS about equally often. On Wix, 98% of sites with a largest shift under 0.01 largest single layout shift score have a good CLS, against 97% of Wix sites with a largest shift of 0.01 to 0.10. Within Wix, sites with a largest shift under 0.01 and a largest shift of 0.01 to 0.10 have a good CLS about equally often.

When a single layout jump blows the entire 0.10 CLS budget

Google's Good CLS threshold is 0.10. Across 1,504 shifting sites (36.7%) whose largest single shift stays below 0.01, 94% pass field CLS, and across 1,500 sites (36.6%) at 0.01 to 0.10, 89% pass. Once a single jump lands between 0.10 and 0.25 (11.8%), good field CLS drops to 72%, and when a single shift exceeds 0.25 (14.8%, 605 sites), only 65% pass field CLS.