WordPress iframe count and the Core Web Vitals

Sites with 1 iframe iframe count per page have a good CLS most often: 87%, against 89% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 80%.

Sites with 2 to 3 iframes iframe count per page have a good INP most often: 98%, against 98% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 95%.

Sites with 1 iframe iframe count per page have a good LCP most often: 68%, against 70% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 65%.

46.5% of WordPress sites use iframe count per page, and 46% of those use 2 to 3 iframes. 1 iframe is 35% of the sites with iframe count, 16.2% of all WordPress sites.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 89% of jQuery sites have a good CLS, against 89% of all sites. On Vue, 72% of sites use 0 iframes, and 89% of Vue sites have a good CLS.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 98% of jQuery sites have a good INP, against 98% of all sites. On Vue, 72% of sites use 0 iframes, and 97% of Vue sites have a good INP.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 69% of jQuery sites have a good LCP, against 70% of all sites. On Vue, 72% of sites use 0 iframes, and 68% of Vue sites have a good LCP.

FrameworkIframe count per page on its sitesGood CLS

All WordPress sites 63,295 sites0 iframes 53%2 to 3 iframes 21%1 iframe 16%89%

Alpine 380 sites0 iframes 35%2 to 3 iframes 27%4+ iframes 20%1 iframe 18%90%

jQuery 60,314 sites0 iframes 53%2 to 3 iframes 22%1 iframe 16%89%

Vue 4,844 sites0 iframes 72%1 iframe 13%2 to 3 iframes 11%89%

React 2,233 sites0 iframes 48%2 to 3 iframes 23%1 iframe 17%4+ iframes 11%85%

0 iframes 2 to 3 iframes 1 iframe 4+ iframes

Does the framework explain the iframe count per page difference?

On jQuery, 87% of sites with 1 iframe iframe count per page have a good CLS, against 92% of jQuery sites with 0 iframes. Within jQuery, sites with 1 iframe have a good CLS less often. On Vue, 87% of sites with 1 iframe iframe count per page have a good CLS, against 90% of Vue sites with 0 iframes. Within Vue, sites with 1 iframe have a good CLS less often.

On jQuery, 98% of sites with 2 to 3 iframes iframe count per page have a good INP, against 99% of jQuery sites with 0 iframes. Within jQuery, sites with 2 to 3 iframes and 0 iframes have a good INP about equally often. On Vue, 97% of sites with 2 to 3 iframes iframe count per page have a good INP, against 97% of Vue sites with 0 iframes. Within Vue, sites with 2 to 3 iframes and 0 iframes have a good INP about equally often.

On jQuery, 67% of sites with 1 iframe iframe count per page have a good LCP, against 72% of jQuery sites with 0 iframes. Within jQuery, sites with 1 iframe have a good LCP less often. On Vue, 69% of sites with 1 iframe iframe count per page have a good LCP, against 68% of Vue sites with 0 iframes. Within Vue, sites with 1 iframe and 0 iframes have a good LCP about equally often.

How embedded iframes destabilize layout and multiply main-thread contexts

Every <iframe> creates an independent browsing context with its own document, styles, and scripts, and frequently resizes asynchronously after load. Across 33,851 sites (53.5%) with 0 iframes, 92% pass field CLS. Adding 1 iframe (16.2%) lowers good CLS to 87%, 2 to 3 iframes (21.2%) drops good CLS to 87%, and 4 or more iframes (9.1%, 5,759 sites) pulls good CLS down to 80%.