WordPress speculation rules posture (prefetch vs prerender) and the Core Web Vitals

Sites with prefetch speculation rules pass all three Core Web Vitals most often: 62%, against 63% of all WordPress sites. The biggest gap is CLS, 91% against 90%.

Sites with prefetch speculation rules have a good LCP most often: 69%, against 70% of all WordPress sites. Sites with prerender speculation rules have it least often, at 69%.

Sites with prefetch speculation rules have a good INP most often: 97%, against 97% of all WordPress sites. Sites with prerender speculation rules have it least often, at 93%.

Sites with prefetch speculation rules have a good CLS most often: 91%, against 90% of all WordPress sites. Sites with prerender speculation rules have it least often, at 88%.

85.1% of WordPress sites use speculation rules, and 99% of those use prefetch.

Vue sets the speculation rules to prefetch on 93% of its sites, and 60% of Vue sites pass all three Core Web Vitals, against 63% of all sites.

Vue sets the speculation rules to prefetch on 93% of its sites, and 67% of Vue sites have a good LCP, against 70% of all sites.

Vue sets the speculation rules to prefetch on 93% of its sites, and 95% of Vue sites have a good INP, against 97% of all sites.

Vue sets the speculation rules to prefetch on 93% of its sites, and 90% of Vue sites have a good CLS, against 90% of all sites.

FrameworkSpeculation rules on its sitesPass all three

WordPress sites with speculation rules 63,293 sitesPrefetch 84%No rules 15%63%

Alpine 380 sitesPrefetch 88%No rules 11%66%

jQuery 60,312 sitesPrefetch 85%No rules 14%62%

Vue 4,844 sitesPrefetch 93%60%

React 2,233 sitesPrefetch 89%55%

Prefetch No rules Prerender

Does the framework explain the speculation rules difference?

On jQuery, 62% of sites with prefetch speculation rules pass all three Core Web Vitals, against 61% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules pass all three about equally often.

On jQuery, 68% of sites with prefetch speculation rules have a good LCP, against 69% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules have a good LCP about equally often.

On jQuery, 97% of sites with prefetch speculation rules have a good INP, against 96% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules have a good INP about equally often.

On jQuery, 90% of sites with prefetch speculation rules have a good CLS, against 89% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules have a good CLS about equally often.

How prefetch, prerender-until-script, and prerender differ in Chrome

A prefetch rule only downloads the next page's HTML document ahead of the click, removing network TTFB on the subsequent navigation while leaving subresources and rendering until after the visitor navigates. A prerender-until-script rule downloads the HTML and subresources and builds the DOM and CSSOM in a hidden renderer, pausing before JavaScript executes. A full prerender rule executes scripts and paints the next page in the background so activation is near-instant.