Speculation posture
The strongest speculation rule the document declares: none, prefetch, prerender-until-script, prerender.
At a glance the headline numbers for Speculation posture
The strongest speculation rule the document declares: none, prefetch, prerender-until-script, prerender.
65.7% of sites declare no speculation rules at all.
Speculation posture who uses what, and how fast each group loads
Little daylight between the groups: every variant sits near 39ms median INP. computed
Passing INP per speculation posture which group passes the INP most often
No variant stands out: pass rates sit between 97% and 100%. computed
Why this matters for the Core Web Vitals, and where to start fixing it
Speculation rules let the browser start the next navigation before the click. Prefetch downloads the next document ahead of time. Prerender goes further and builds the whole next page in a hidden renderer, so navigating to it is a swap instead of a load. Prerender-until-script is the cautious middle: build the page, hold the scripts.
Done right, the next page's LCP is near-instant because it painted before the visitor arrived. The cost is speculative work: prerendering pages nobody visits burns server and client resources. That trade is what eagerness controls.
How does this affect the Core Web Vitals?
The choice barely moves the INP: 100% pass at best, 97% at worst. This signal does not separate passing sites from failing ones.
The split is bigger on CLS. With Prerender until script, 97% of sites pass it. With None, 78% do.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.