Speculation rules posture on React sites

Sites with prefetch speculation rules pass all three Core Web Vitals most often: 68%, against 63% of all React sites. The biggest gap is CLS, 86% against 80%.

Sites with prefetch speculation rules have a good LCP most often: 78%, against 79% of all React sites.

Sites with prefetch speculation rules have a good INP most often: 100%, against 99% of all React sites.

Sites with prefetch speculation rules have a good CLS most often: 86%, against 80% of all React sites.

83.4% of React sites use speculation rules, and 93% of those use prefetch.

Wix sets the speculation rules to prefetch on 90% of its sites, and 88% of Wix sites pass all three Core Web Vitals, against 63% of all sites.

Wix sets the speculation rules to prefetch on 90% of its sites, and 92% of Wix sites have a good LCP, against 79% of all sites.

Wix sets the speculation rules to prefetch on 90% of its sites, and 100% of Wix sites have a good INP, against 99% of all sites.

Wix sets the speculation rules to prefetch on 90% of its sites, and 96% of Wix sites have a good CLS, against 80% of all sites.

PlatformSpeculation rules on its sitesPass all three

All React sites 9,570 sitesPrefetch 78%No rules 17%63%

Wix 5,824 sitesPrefetch 90%88%

WordPress 2,342 sitesPrefetch 89%51%

Prefetch No rules Prerender until script Prerender

Does the platform explain the speculation rules difference?

On Wix, 88% of sites with prefetch speculation rules pass all three Core Web Vitals, against 92% of Wix sites with prerender-until-script. Within Wix, sites with prefetch and prerender-until-script pass all three about equally often. On WordPress, 51% of sites with prefetch speculation rules pass all three Core Web Vitals, against 55% of WordPress sites with no. Within WordPress, sites with prefetch and no pass all three about equally often.

On Wix, 92% of sites with prefetch speculation rules have a good LCP, against 94% of Wix sites with prerender-until-script. Within Wix, sites with prefetch and prerender-until-script have a good LCP about equally often. On WordPress, 65% of sites with prefetch speculation rules have a good LCP, against 75% of WordPress sites with no. Within WordPress, sites with prefetch and no have a good LCP about equally often.

On Wix, 100% of sites with prefetch speculation rules have a good INP, against 100% of Wix sites with prerender-until-script. Within Wix, sites with prefetch and prerender-until-script have a good INP about equally often. On WordPress, 100% of sites with prefetch speculation rules have a good INP, against 98% of WordPress sites with no. Within WordPress, sites with prefetch and no have a good INP about equally often.

On Wix, 96% of sites with prefetch speculation rules have a good CLS, against 97% of Wix sites with prerender-until-script. Within Wix, sites with prefetch and prerender-until-script have a good CLS about equally often. On WordPress, 76% of sites with prefetch speculation rules have a good CLS, against 72% of WordPress sites with no. Within WordPress, sites with prefetch and no 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.