WordPress speculation rules and the Core Web Vitals
Conservative, moderate, eager or immediate: which speculation rules sites use, and whether those sites pass LCP, INP and CLS more often.
14.9% of WordPress sites have no speculation rules. Of the 85.1% that do, 1% use moderate, and 60% of those sites pass all three Core Web Vitals, against 60% of all WordPress sites.
14.9% of WordPress sites have no speculation rules. Of the 85.1% that do, 1% use moderate, and 79% of those sites have a good LCP, against 76% of all WordPress sites.
14.9% of WordPress sites have no speculation rules. Of the 85.1% that do, 99% use conservative, and 100% of those sites have a good INP, against 100% of all WordPress sites.
14.9% of WordPress sites have no speculation rules. Of the 85.1% that do, 99% use conservative, and 78% of those sites have a good CLS, against 78% of all WordPress sites.
Core Web Vitals pass rate
Sites with moderate speculation rules pass all three Core Web Vitals most often: 60%, against 60% of all WordPress sites. The biggest gap is LCP, 79% against 76%.
Sites with moderate speculation rules have a good LCP most often: 79%, against 76% of all WordPress sites. Sites with conservative rules have it least often, at 75%.
Sites with conservative speculation rules have a good INP most often: 100%, against 100% of all WordPress sites. Sites with moderate rules have it least often, at 99%.
Sites with conservative speculation rules have a good CLS most often: 78%, against 78% of all WordPress sites. Sites with moderate rules have it least often, at 77%.
Speculation rules usage
85.1% of WordPress sites use speculation rules, and 99% of those use conservative. Moderate is 1% of the sites with rules, 0.7% of all WordPress sites.
Speculation rules per framework
On jQuery, 85% of sites use conservative speculation rules, and 60% of jQuery sites pass all three Core Web Vitals, against 60% of all sites. On Vue, 92% of sites use conservative, and 57% of Vue sites pass all three.
On jQuery, 85% of sites use conservative speculation rules, and 75% of jQuery sites have a good LCP, against 76% of all sites. On Vue, 92% of sites use conservative, and 75% of Vue sites have a good LCP.
On jQuery, 85% of sites use conservative speculation rules, and 100% of jQuery sites have a good INP, against 100% of all sites. On Vue, 92% of sites use conservative, and 99% of Vue sites have a good INP.
On jQuery, 85% of sites use conservative speculation rules, and 77% of jQuery sites have a good CLS, against 78% of all sites. On Vue, 92% of sites use conservative, and 75% of Vue sites have a good CLS.
Alpine 380 sitesConservative 88%No rules 11%69%82%99%81%
jQuery 60,312 sitesConservative 85%No rules 14%60%75%100%77%
Vue 4,844 sitesConservative 92%57%75%99%75%
React 2,233 sitesConservative 89%50%66%100%75%Speculation rules or the framework
Does the framework explain the speculation rules difference?
On jQuery, 60% of sites with conservative 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, 75% of sites with conservative speculation rules have a good LCP, against 79% of jQuery sites without speculation rules. Within jQuery, sites with conservative speculation rules have a good LCP less often.
On jQuery, 100% of sites with conservative speculation rules have a good INP, against 99% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules have a good INP about equally often.
On jQuery, 77% of sites with conservative speculation rules have a good CLS, against 75% of jQuery sites without speculation rules. Within jQuery, sites with and without speculation rules have a good CLS about equally often.
How much speculation rules speed up the next page
Speculation rules only speed up the page a visitor opens next, not the page they land on, and Chrome's field data counts both. A prefetch fetches the next page's HTML early, which takes time off its TTFB and its LCP. A prerender also builds the next page before the click, so it can open with an LCP close to zero and its layout shifts happen out of sight. In Shopify's test, moderate cut the median LCP of the next page by 228 ms on desktop compared with conservative, and by 24 ms on phones.
Understanding speculation rules eagerness
Use eager. Sites with eager speculation rules pass all three Core Web Vitals most often, and the theory fits: the earlier Chrome starts, the more of the next page is ready when the visitor clicks. Almost all of those sites are Wix sites, so part of that lead is the platform. The cost is pages loaded that nobody opens, so check that your server can take the extra requests. Conservative waits until the visitor presses a link. Moderate starts after a 200 ms hover on desktop, and on a phone half a second after scrolling stops near a link. Eager starts after a 10 ms hover on desktop, and on a phone once a link has been on screen for 50 ms. Immediate starts as soon as Chrome reads the rule. On WordPress, core uses conservative, which made no visible difference in this data; the wp_speculation_rules_configuration filter switches it to eager.
By Arjen Karel · 63,295 crawled WordPress sites (17,005 with desktop Chrome field data, 63,293 sites with speculation rules, October 2026). How we measured.