CODEWITHSUNDEEP
javascriptcssperformancefirefox
Casey Jordan
Casey Jordan

Reputation: 1254

How can I determine why Firefox is burning CPU "Recalculating Style" when app idle?

I have a situation where the CPU used by firefox jumps up to about 50% and does not decrease when I go to my app's tab. The app is idle, I am not clicking on anything, and no requests are being made. Yet the CPU does not drop.

I used Firebug to profile what was going on, but it returned that there was no javascript calls.

So then I used the most recent Performance profiler in Firefox 40. Running the profiler for about 5 seconds then stopping showed that the gecko engine was sending lots of calls to "Recalculate Style", specifically the hint given was that it is related to CSS Animations. See screenshot:

enter image description here

I need to find out what is causing this because I believe it is inherently slowing my app down. However, I am not sure what to do next in order to track down the issue.

Thanks

Upvotes: 2

Views: 1450

Answers (1)

Casey Jordan
Casey Jordan

Reputation: 1254

Problem turned out to be an animation that was off screen but Firefox was still burning CPU calculating the keyframes etc.

Upvotes: 2

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