Speculation rules eagerness 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.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 8% use eager, and 89% of those sites pass all three Core Web Vitals, against 70% of all sites.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 8% use eager, and 94% 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, 89% use conservative, and 97% of those sites have a good INP, against 92% of all sites.
Two in three sites, 65.1%, have no speculation rules. Of the 34.9% that do, 8% use eager, and 98% of those sites have a good CLS, against 89% of all sites.
Core Web Vitals pass rate
Sites with eager speculation rules pass all three Core Web Vitals most often: 89%, against 70% of all sites. The biggest gap is LCP, 94% against 82%.
Sites with eager speculation rules have a good LCP most often: 94%, against 82% of all sites. Sites with conservative rules have it least often, at 70%.
Sites with conservative speculation rules have a good INP most often: 97%, against 92% of all sites. Sites with moderate rules have it least often, at 92%.
Sites with eager speculation rules have a good CLS most often: 98%, against 89% of all sites. Sites with conservative rules have it least often, at 91%.
Speculation rules usage
One in three sites uses speculation rules, and nine in ten of those use conservative. Eager is 8% of the sites with rules, 2.8% of all sites.
Understanding speculation rules eagerness
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.
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.
How speculation rules plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,507 sites 84.3% of WordPress sites emit conservative speculation rules (63% CWV pass vs 64% with none).
WordPress 6.8+ enables Speculative Loading in core with prefetch and conservative eagerness by default, configurable with the wp_speculation_rules_configuration filter. Across WordPress, 84.3% of sites emit conservative rules (63% passing all three Core Web Vitals) compared with 64% on sites with no inline rules.
Shopify 8,573 stores 90.2% of Shopify stores ship no inline speculation rules tag (85% all-three CWV pass rate).
Across Shopify storefronts, 90.2% have no inline <script type="speculationrules"> tag in initial HTML, and 85% of stores pass all three Core Web Vitals.
React & Next.js 9,570 sites 60.1% of React sites emit eager speculation rules and 16.6% emit no inline tag.
Next.js App Router provides route prefetching on <Link> components in JavaScript. Across React sites in the dataset, 60.1% carry inline eager speculation rules, 22.4% carry conservative rules, and 16.6% have no inline speculation rules tag.
By Arjen Karel · 210,902 crawled sites (126,761 with phone Chrome field data, 206,207 sites with speculation rules, October 2026). How we measured.