2033282 - High CPU consumption on google search result expansion - WR sw_compositor recomposites the window due to offscreen animation

Status: ASSIGNED

(Core :: Graphics: WebRender, defect)

Description

On Windows 10 with 16GBytes of memory, I browse:

Google search

This is a normal google search that has an AI overview at the top of the results.
When the search results are displayed, then CPU consumption is normal, in the range from 0.2% to roughly 1%. However, when I click on the "Show more" button, then the result expands and CPU consumption jumps to 40% to 60% and my computer fans start making noise.

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Can you get a profile of this behavior? (Https://profiler.firefox.com)
Thanks!

Comment 2

[bht237]

Profile permalink

Comment 3

[bht237]

Profile 2 permalink

Comment 4

[Andrew McCreight [:mccr8]]

I fixed up your links for now, but FYI the way you need to do markup for a link is like this: [link description](https://example.com)

Comment 5

[Bas Schouten (:bas.schouten)]

Hi!

It's hard to tell from the current profile what's going on.

Is there any chance you can take a profile using the 'graphics' preset? (You can select it from the popup menu that you can open with the profiler button)

Thanks!

Comment 6

[Markus Stange [:mstange]]

I believe the composites are triggered by the gradient animation around the "Dive deeper in AI Mode" button. However, this button is offscreen. So I think the Firefox bug here is that, with the WebRender sw_compositor, we end up compositing even if the changes only affect clipped-out tiles.

Comment 7

[Bas Schouten (:bas.schouten)]

It seems to me that if the CSS animation with the rotated rectangles doesn't terminate when the button is scrolled out of the view (the way it is in the user's profile).

Comment 8

[Bas Schouten (:bas.schouten)]

It seems to me that if the CSS animation with the rotated rectangles doesn't terminate when the button is scrolled out of the view (the way it is in the user's profile).

The Performance Impact Calculator has determined this bug's performance impact to be medium. If you'd like to request re-triage, you can reset the Performance Impact flag to "?" or needinfo the triage sheriff.

Platforms: [x] Windows [x] macOS [x] Linux
Websites affected: Major
Resource impact: Some
[x] Able to reproduce locally

Comment 9

[Lee Salzman [:lsalzman]]

Glenn, can you take a look?

Comment 11

[Lee Salzman [:lsalzman]]

Bug 2032772 is very similar, other than that it notes even with HW accel there is in fact still very high CPU churn too, just which is magnified even further in SW.

Comment 12

[Georgi H. Yordanov]

(In reply to Lee Salzman [:lsalzman] from comment #11)

Bug 2032772 is very similar, other than that it notes even with HW accel there is in fact still very high CPU churn too, just which is magnified even further in SW.

Closing my earlier-reported Bug 2032772 was actually a correct move. Update as of 21 Apr 2026, before Firefox 149.0.2 was updated to 150.0.0:

Perhaps some microupdate occurred in the meantime because the CPU hogging by Firefoxes' GPU process stopped while part of Google's AI Search page was still seen in the background. I haven't made any changes to my Firefox Settings or Extensions.

Not an issue in v.150.0.0, either.

Comment 13

[Glenn Watson [:gw]]

Attachment: Bug 2033282 - Skip composite_native when dirty rects is empty

Comment 14

[Glenn Watson [:gw]]

This seems to fix the high CPU usage for this scenario on swgl. I have been unable to test on CI as try server is just returning 502/503 at the moment, so will run a more thorough test later.

Comment 16

[Glenn Watson [:gw]]

Attachment: Bug 2033282 - Skip SwCompositor composition when no native compositor and dirty region is empty

Comment 17

[Jamie]

I have the same issue, the only way I found to avoid it was with a uBlock filter to stop google's animation from triggering via:
||www.gstatic.com/searchbox-team/eclipse_wave_blurred_rects_f2dcf436ae9c2b05017fd88933a1b6ad.png$image

It seems to stem from the SVG https://www.gstatic.com/searchbox-team/eclipse_wave_blurred_rects_f2dcf436ae9c2b05017fd88933a1b6ad.png

<mask>
<linearGradient>
<clipPath>
<filter>
<feGaussianBlur stdDeviation="15">
<use>
<image class="Wrq4d">

Over about 5 seconds, Firefox profiling recorded:

x596 MozAfterPaint events
x600 DisplayList / WebRender display list updates
x598 paints of https://www.gstatic.com/searchbox-team/eclipse_wave_blurred_rects_f2dcf436ae9c2b05017fd88933a1b6ad.png
CSS animation named rotate-glow-rects
Target element: image ... class='Wrq4d' with animation property: rotate & compositor: true

Hope it helps

Comment 18

[Robert]

I have the same issue with AI overview when expanding show more. Firefox main pid goes from ~%5 to 500% CPU thread usage while staying on the same tab.
I'm on firefox-150.0-1.fc44.x86_64, Mesa 26.0.3-4, amd-gpu-firmware-20260410-1.fc44.noarch

Comment 19

[Daniel M]

Can confirm this issue on 150.0.1 under Linux. It's pretty bad as, if you leave a tab with this active, it can quickly kill your battery life.

Comment 20

[jtl]

This bug is SERIOUS and need to be fixed pronto and also fixed in ESR. If its not fixed, its just going to be another nail in the coffin for Firefox.