305251 2026-01-10 00:39:46 -0800 High INP (Interaction to Next Paint) for interactions with no immediate screen updates 2026-01-24 01:31:38 -0800 1 1 1 Unclassified WebKit WebCore Misc. Safari 16 Mac (Apple Silicon) macOS 15 RESOLVED FIXED InRadar P2 Normal --- 1 barry franco_vieira franco_vieira rreno ryan webkit-bug-importer oldest_to_newest 2170877 0 barry 2026-01-10 00:39:46 -0800 When I visit this simple demo page: https://www.tunetheweb.com/experiments/event-timing/ and click on the `<h1>` I see PerformanceEventTiming entries (used to measure INP) of 504ms or more when it should be much closer to 150ms. I even see it when there are no event handlers at all: https://www.tunetheweb.com/experiments/event-timing/no-event-handlers.html Curiously I don't often see it with this more complex page: https://chrome.dev/inp-demo/ That has a widget causing constant frame updates - Maybe that is why? So here's a copy of my origin demo that does a screen update: https://www.tunetheweb.com/experiments/event-timing/with-update.html And now pointerup/click is as expected, and usually too fast to even register (except for the first first-input). We still see a somewhat slow pointerdown, so let's add an event handler to that: https://www.tunetheweb.com/experiments/event-timing/with-both-updates.html And now that's also fixed. If there is no screen update to make, then `first-input` and `event` should return quickly/almost instantly rather than appear to show a poor responsiveness. I can't see this explicitly mentioned in the spec (https://w3c.github.io/event-timing/#sec-performance-event-timing) but it's how Chrome and Firefox work. 2171263 1 ap 2026-01-12 13:54:33 -0800 Thank you for the report! 2171265 2 webkit-bug-importer 2026-01-12 13:59:55 -0800 <rdar://problem/168016487> 2171848 3 franco_vieira 2026-01-14 10:03:14 -0800 Pull request: https://github.com/WebKit/WebKit/pull/56574 2174714 4 ews-feeder 2026-01-24 01:31:36 -0800 Committed 306142@main (8af8a7cdd78d): <https://commits.webkit.org/306142@main> Reviewed commits have been landed. Closing PR #56574 and removing active labels.