Able to reproduce the issue on Mac 10.11.5, Ubuntu 14.04 using latest canary 53.0.2746.0, stable 50.0.2661.102.Observed that high CPU usage on Reddit "Top scoring links" page.

This is non regression issue seen from M-32(32.0.1700.107).Hence, marking it as untriaged.

Note:Working fine on Windows 7.

Could anyone from dev team look into this issue please.

Moving this nonessential bug to the next milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

i think it's because of two CSS animations on the page

scroll down until you see "moderators" in the right side panel, then enable paint flashing in the dev tools (i attached a still of it)

the first one (spinning teddy bear) has a text-indent value of -9999px, causing it to repaint a needlessly large area

the second one (animated progress bar) just runs at 60fps all the time

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	Untitled.png 18.7 KB View Download

Thanks.  Can someone from CSS help triage this?  TaskManager is not the right component for pages that have high CPU usage.

Setting update level to quarterly since this is a non-regression issue.

These animations (pointed out by #3) seem to be causing main thread repaints of the entire page.

Inspecting the DevTools timeline shows 0.3ms in rendering and 1.7ms in painting every frame. It's painting 945x4047 which (based on the screenshot) is the entire page. The tile workers aren't being used at all.

Hopefully one day we'll get background-position animations composited like transform and opacity...

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	trace.png 212 KB View Download

I'm not seeing anything unexpected on Linux 52.0.2743.49. Paint flashing in devtools just show repaint of the image areas, not an entire layer. Low CPU usage. Am I missing something?

Running Linux Chrome 52 I see 25-28% CPU usage in Chrome's task manager (animations not visible on page).

I can't explain the disparity between the repaint flashes and paint profiler but I would trust that the tracing data is accurate. See above screenshot.

I'll own it for a while. I'll dump the SkPictures and see what's happening.

This issue has been moved once and is lower than Pri-1. Removing the milestone.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Ping for schenney - is this still a valid bug?

I think we WontFix this. It was a specific reddit link and may well just be expensive invalidation since we are not actually repainting. We've done a bunch of work speeding up invalidation and there's not much specific to be done for this.