v138 · performance
Speculation rules: mobile "moderate" eagerness improvements
On mobile, "moderate" eagerness speculation rules prefetches and prerenders now trigger when a link enters the viewport and passes other conditions that indicate that it's more likely to be clicked. The previous behavior, of waiting until pointerdown, was the same as "conservative" eagerness. This new behavior is more useful as it better reflects author i
concepts
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Mobile Moderate Tuning
Speculation rules' moderate eagerness on mobile triggers earlier for likely-clicked targets, lifting prerender hit rate.
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Tap vs hover
The actual heuristic change: mobile moderate eagerness now arms on
pointerdown/touchstartinstead of waiting for the synthesised click. Counts armed and warmed events side by side. -
Touch latency bench
Measures the actual pointerdown → click gap on a touch device, with a live moderate-eagerness rule armed. The gap is the speculation window the v138 change reclaims.
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Eagerness comparison
Side-by-side comparison of all four eagerness levels — conservative, moderate, eager, immediate — showing trigger event, typical delay, and prerender hit rate. Interactive simulation fires hover/pointerdown/viewport-entry events and shows which levels would have armed in time for the navigation.
why it shipped
On mobile, "moderate" eagerness speculation rules prefetches and prerenders now trigger when a link enters the viewport and passes other conditions that indicate that it's more likely to be clicked. The previous behavior, of waiting until pointerdown, was the same as "conservative" eagerness. This new behavior is more useful as it better reflects author i