The State of Web Vitals

Speculation posture

The strongest speculation rule the document declares: none, prefetch, prerender-until-script, prerender.

Field data PhoneDesktopAll Scope All sites Q2 2026 edition · Desktop field outcomes
Metric LCP INP CLS
1

At a glance the headline numbers for Speculation posture

The strongest speculation rule the document declares: none, prefetch, prerender-until-script, prerender.

4
Categories
185,226 sites
65.7%
Top share
none
0.03
Top CLS
Median for none

65.7% of sites declare no speculation rules at all.

The State of Web Vitals · Q2 2026 · 189,915 sites · desktop field datacorewebvitals.io/state-of-cwv
2

Speculation posture who uses what, and how stable each group is

Median CLS
0
0.05
0.10
0.15
0.20
0.25
prerender_until_script0.010% of sites
none0.0366% of sites
prefetch0.0334% of sites
prerender0.031% of sites
VariantShare of sitesMedian
prerender_until_script 491 sites
0%
0.01
none 121,738 sites
66%
0.03
prefetch 62,089 sites
34%
0.03
prerender 908 sites
1%
0.03

Little daylight between the groups: every variant sits near 0.01 median CLS. computed

The State of Web Vitals · Q2 2026 · 189,915 sites · desktop field datacorewebvitals.io/state-of-cwv
3

Passing CLS per speculation posture which group passes the CLS most often

VariantSitesPassing CLSCLS
Prerender until script 0.3% 491 97% 0.01
Prefetch 33.5% 62,089 78% 0.03
Prerender 0.5% 908 78% 0.03
None 65.7% 121,738 78% 0.03
Good Needs Improvement Poor Sorted best-passing first · median colored by its own rating · pass = good CLS (0.1 at p75) · one value per site

97% of Prerender until script sites pass CLS. None trails 19 points behind. computed

The State of Web Vitals · Q2 2026 · 189,915 sites · desktop field datacorewebvitals.io/state-of-cwv
4

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?

Speculation posture correlates with the CLS. With Prerender until script, 97% of sites pass the CLS. With None, 78% do. The causal link is weak: the choice mostly marks what kind of site made it.

Go fix it Speculation rules → The prerender-until-script speculation rule → View transitions and web performance →
Related signals Speculation eagerness → Chrome field data from 189,915 sites, representing millions of real page loads · How we measured