WordPress iframe count and the Core Web Vitals

Sites with 2 to 3 iframes iframe count per page have a good CLS most often: 77%, against 78% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 73%.

Sites with 2 to 3 iframes iframe count per page have a good INP most often: 100%, against 100% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 99%.

Sites with 1 iframe iframe count per page have a good LCP most often: 76%, against 76% of all WordPress sites. Sites with 4+ iframes iframe count have it least often, at 72%.

46.5% of WordPress sites use iframe count per page, and 46% of those use 2 to 3 iframes.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 77% of jQuery sites have a good CLS, against 78% of all sites. On Vue, 72% of sites use 0 iframes, and 75% of Vue sites have a good CLS.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 100% of jQuery sites have a good INP, against 100% of all sites. On Vue, 72% of sites use 0 iframes, and 99% of Vue sites have a good INP.

On jQuery, 53% of sites use 0 iframes iframe count per page, and 75% of jQuery sites have a good LCP, against 76% of all sites. On Vue, 72% of sites use 0 iframes, and 75% 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%78%

Alpine 380 sites0 iframes 35%2 to 3 iframes 27%4+ iframes 20%1 iframe 18%81%

jQuery 60,314 sites0 iframes 53%2 to 3 iframes 22%1 iframe 16%77%

React 2,233 sites0 iframes 48%2 to 3 iframes 23%1 iframe 17%4+ iframes 11%75%

Vue 4,844 sites0 iframes 72%1 iframe 13%2 to 3 iframes 11%75%

0 iframes 2 to 3 iframes 1 iframe 4+ iframes

Does the framework explain the iframe count per page difference?

On jQuery, 77% of sites with 2 to 3 iframes iframe count per page have a good CLS, against 80% of jQuery sites with 0 iframes. Within jQuery, sites with 2 to 3 iframes have a good CLS less often. On Vue, 76% of sites with 2 to 3 iframes iframe count per page have a good CLS, against 76% of Vue sites with 0 iframes. Within Vue, sites with 2 to 3 iframes and 0 iframes have a good CLS about equally often.

On jQuery, 100% of sites with 2 to 3 iframes iframe count per page have a good INP, against 100% 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, 100% of sites with 2 to 3 iframes iframe count per page have a good INP, against 99% 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, 75% of sites with 1 iframe iframe count per page have a good LCP, against 78% of jQuery sites with 0 iframes. Within jQuery, sites with 1 iframe have a good LCP less often. On Vue, 74% of sites with 1 iframe iframe count per page have a good LCP, against 76% 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, 80% pass field CLS. Adding 1 iframe (16.2%) lowers good CLS to 76%, 2 to 3 iframes (21.2%) drops good CLS to 77%, and 4 or more iframes (9.1%, 5,759 sites) pulls good CLS down to 73%.