Open Bug 1934498 Opened 2 months ago Updated 2 months ago

High CPU load (~180%) on "What's New" page even with the window in the background

Categories

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

defect

Tracking

()

People

(Reporter: whimboo, Unassigned)

References

(Blocks 3 open bugs, )

Details

(Keywords: power)

Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:135.0) Gecko/20100101 Firefox/135.0 ID:20241128215411

I noticed that issue over the weekend because the battery of my MBP drained quite fast. One of the last things I did on Friday last week is to update Firefox Nightly to check if a reported regression was fixed. After the restart I missed to close the tab for the What's New page that always gets opened after an update because it was added to a different window, and which I moved into the background. Then over the weekend this window was completely behind all the other windows (but Nightly was not hidden). When I noticed the high CPU load I quickly found out that it's the What's New page that is causing it, and the only way to prevent it was to actively put the tab as background tab. Why do we still render the animation as used by the current site even when the window is completely covered by other windows?

Here a Gecko profile: https://share.firefox.dev/3OzJPrV

I tried as well in both Google Chrome and Safari and for them the CPU utilization is way lower but as well stays high when the window is completely covered by another one.

Blocks: wr-blob-perf

(In reply to Henrik Skupin [:whimboo][⌚️UTC+2] from comment #0)

Why do we still render the animation as used by the current site even when the window is completely covered by other windows?

Most likely because window occlusion detection is not working correctly on Mac, we discussed it a bit in bug 1779557.

Blocks: 1779557
Severity: -- → S3
Priority: -- → P3

Please note that this bug is not primarily about the high CPU load while the window is in background but in general compared to other browsers.

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