Speculation rules posture (prefetch vs prerender) and the Core Web Vitals
Prefetch (34.1%), prerender (0.6%), prerender-until-script (0.3%), or no speculation rules (65.1%): how far ahead sites prepare the next navigation and how each posture performs on LCP, INP, and CLS.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 1% use prerender-until-script, and 91% of those sites pass all three Core Web Vitals, against 71% of all sites.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 1% use prerender-until-script, and 95% of those sites have a good LCP, against 82% of all sites.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 98% use prefetch, and 98% of those sites have a good INP, against 95% of all sites.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 1% use prerender-until-script, and 98% of those sites have a good CLS, against 88% of all sites.
Core Web Vitals pass rate
Sites with prerender-until-script speculation rules pass all three Core Web Vitals most often: 91%, against 71% of all sites. The biggest gap is LCP, 95% against 82%.
Sites with prerender-until-script speculation rules have a good LCP most often: 95%, against 82% of all sites. Sites with prefetch speculation rules have it least often, at 73%.
Sites with prefetch speculation rules have a good INP most often: 98%, against 95% of all sites. Sites with prerender speculation rules have it least often, at 94%.
Sites with prerender-until-script speculation rules have a good CLS most often: 98%, against 88% of all sites. Sites with prerender speculation rules have it least often, at 85%.
Speculation rules usage
One in three sites uses speculation rules, and 98% of those use prefetch. Prerender-until-script is 1% of the sites with speculation rules, 0.3% of all sites.
Understanding speculation rules posture
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.
Use prefetch with moderate eagerness as your site-wide baseline, and use prerender or prerender-until-script on high-probability next navigations where your server and third-party scripts support background rendering. Across the dataset, 34.1% of sites use prefetch (66% passing all three Core Web Vitals, largely WordPress 6.8 sites on conservative eagerness), 0.3% use prerender-until-script (91% passing all three, driven by Wix), and 0.6% use full prerender (67% passing all three). Always exclude cart, checkout, logout, and state-mutating URLs from both prefetch and prerender rules.
How speculation rules plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,507 sites 84.6% of WordPress sites emit document prefetch speculation rules (63% CWV pass rate).
WordPress 6.8+ enables Speculative Loading in core with a conservative prefetch posture by default. Across WordPress, 84.6% of sites with speculation rules use prefetch (63% passing all three Core Web Vitals) and 0.6% use prerender.
Shopify 8,573 stores 90.2% of Shopify stores ship no inline <script type="speculationrules"> tag (88% CWV pass rate).
Across Shopify storefronts, 90.2% emit no inline <script type="speculationrules"> element in initial HTML, with 88% passing all three Core Web Vitals overall.
React & Next.js 9,570 sites Among React & Next.js sites with speculation rules, 77.5% use prefetch and 5.5% use prerender_until_script.
Across React sites in the dataset, 77.5% emit prefetch rules (79% CWV pass rate), 5.5% emit prerender_until_script (91% CWV pass rate), and 16.6% emit no inline speculation rules tag.
By Arjen Karel · 210,902 crawled sites (196,263 with all devices Chrome field data, 206,207 sites with speculation rules, October 2026). How we measured.