1614691 - Don't re-build the hit-test tree every frame when nothing moves

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement, P3)

Description

[Nicolas Silva [:nical]]

Building the hit test tree is usually a small part of the frame building time. However since we do it every frame, it can add up to a not-so-trivial amount of wasted power usage when watching a video, for example (~0.15ms of cpu work per frame on average on a mid/low end atom CPU).

It should be relatively simple to detect that no animated properties changed and avoid re-building the hit-test tree.

Comment 1

[Nicolas Silva [:nical]]

We could probably do even better but we don't re-build the hit-test tree excessively. We mostly do it when scrolling and and scene building, but not every frame during video playback.