WordPress layout shift causes (CLS attribution) and field CLS
Element box growth (78.5%), sibling displacement (33.5%), web font reflow (24.1%), unsized media (4.4%), and late embed growth (0.7%) across 44,905 sites with recorded layout shifts.
24.1% of WordPress sites use web font reflow layout shift causes, and 76% of those sites have a good CLS, against 78% of all WordPress sites.
CLS pass rate
Sites with web font reflow layout shift causes have a good CLS most often: 76%, against 78% of all WordPress sites. Sites with late embed growth shift causes have it least often, at 56%.
Layout shift causes usage
Element box growth is the most used: 78.5% of WordPress sites. Web font reflow is 24.1% of WordPress sites.
Layout shift causes per framework
On jQuery, 79% of sites use element box growth layout shift causes, and 77% of jQuery sites have a good CLS, against 78% of all sites. On Vue, 80% of sites use element box growth, and 75% of Vue sites have a good CLS.
Layout shift causes or the framework
Does the framework explain the layout shift causes difference?
On jQuery, 76% of sites with web font reflow layout shift causes have a good CLS, against 72% of jQuery sites with element box growth. Within jQuery, sites with web font reflow have a good CLS more often. On Vue, 76% of sites with web font reflow layout shift causes have a good CLS, against 70% of Vue sites with element box growth. Within Vue, sites with web font reflow and element box growth have a good CLS about equally often.
How different DOM mutations translate into field CLS failures
Not all lab layout shifts hurt real users equally. Sites whose shifts come from web font swaps (24.1%) pass field CLS 76% of the time because line-height adjustments are small. Element box growth (78.5%, 73% good CLS) and displaced siblings (33.5%, 73% good CLS) cause moderate drops, while late iframe and embed growth (0.7%) pulls field CLS down to 56% (median CLS 0.09).
Understanding layout shift causes
Eliminate late embed and banner growth first by reserving min-height containers for ad slots, promo bars, and third-party widgets. While 78.5% of shifting sites see element box growth (73% good CLS) and 24.1% see font swap reflow (76% good CLS), sites with unreserved iframe or embed growth (0.7%) pass field CLS only 56% of the time.
By Arjen Karel · 63,295 crawled WordPress sites (17,005 with desktop Chrome field data, 44,905 sites with layout shift causes, October 2026). How we measured.