Shopify iframe loading attributes and the Core Web Vitals
Default eager iframes (99.0%) versus loading="lazy" iframes (3.8%): how third-party embed scheduling affects Largest Contentful Paint across the 6,485 sites that use iframes.
99.0% of Shopify sites use default eager iframe loading, and 95% of those sites have a good LCP, against 96% of all Shopify sites.
99.0% of Shopify sites use default eager iframe loading, and 95% of those sites have a good INP, against 96% of all Shopify sites.
Core Web Vitals pass rate
Sites with default eager iframe loading have a good LCP most often: 95%, against 96% of all Shopify sites. Sites with loading="lazy" iframe loading have it least often, at 95%.
Sites with default eager iframe loading have a good INP most often: 95%, against 96% of all Shopify sites. Sites with loading="lazy" iframe loading have it least often, at 95%.
Iframe loading usage
Default eager is the most used: 99.0% of Shopify sites.
How iframe loading affects the four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between default eager and loading="lazy" sits in element render delay: 307 ms median for default eager against 276 ms for loading="lazy". Overall median field LCP is 1.4s for default eager (TTFB 392 ms, load delay 599 ms, load duration 207 ms, render delay 307 ms) versus 1.3s for loading="lazy".
Across the four LCP sub-parts in Chrome's field data, the largest gap between default eager and loading="lazy" sits in element render delay: 307 ms median for default eager against 276 ms for loading="lazy". Overall median field LCP is 1.4s for default eager (TTFB 392 ms, load delay 599 ms, load duration 207 ms, render delay 307 ms) versus 1.3s for loading="lazy".
Iframe loading per framework
jQuery sets the iframe loading to default eager on 99% of its sites, and 94% of jQuery sites have a good LCP, against 96% of all sites.
jQuery sets the iframe loading to default eager on 99% of its sites, and 95% of jQuery sites have a good INP, against 96% of all sites.
Vue 753 sitesDefault eager iframe (no loading="lazy") 99%95%94%
jQuery 2,638 sitesDefault eager iframe (no loading="lazy") 99%94%95%Iframe loading or the framework
Does the framework explain the iframe loading difference?
On jQuery, 93% of sites with default eager iframe loading have a good LCP, against 90% of jQuery sites with loading="lazy". Within jQuery, sites with default eager and loading="lazy" have a good LCP about equally often.
On jQuery, 95% of sites with default eager iframe loading have a good INP, against 95% of jQuery sites with loading="lazy". Within jQuery, sites with default eager and loading="lazy" have a good INP about equally often.
How embedded iframes compete for network and main-thread budget
Every eager iframe initializes a nested browsing context that fetches its own HTML, stylesheets, and scripts during page startup. Among iframe-using sites, 99.0% include default eager iframes (95% good LCP, 1.3s median LCP) - often lightweight analytics or payment sandboxes - while 3.8% use loading="lazy" (95% good LCP, 1.3s median LCP), predominantly on article pages embedding heavy video players or maps.
Understanding iframe loading
Add loading="lazy" to all visible below-the-fold video, map, and social iframes, or replace them with a click-to-load poster facade. Among sites with iframes, 99.0% ship default eager iframes (95% good LCP) and 3.8% ship loading="lazy" iframes (95% good LCP). Avoid putting loading="lazy" on hidden zero-pixel auth or analytics sandboxes, and never leave visible third-party media embeds eager during initial page load.
By Arjen Karel · 8,246 crawled Shopify sites (8,062 with all devices Chrome field data, 6,485 sites with iframe loading, October 2026). How we measured.