User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:28.0) Gecko/20100101 Firefox/28.0 (Beta/Release) Build ID: 20140123004002 Steps to reproduce: On my web page I have a <span> tag which has the following CSS: background: url(my_animation.gif); display: table-cell; I'm using Firefox Aurora 28.0a2 (2014-01-23) on Mac OSX 10.8.4. Actual results: When viewing this page, my CPU usage spikes to 80-90%. If I remove either the background or the display values (via development tools), the CPU jumps down to a reasonable 5-10%. Expected results: Having an animated GIF inside a table-cell element should not affect the CPU as much as it does.
Evgueni, can you attach an example page where this happens -- a reduced test case? Or, a link to your page would also be helpful. Thanks!
Sure thing. Here is a test case: http://jsfiddle.net/2ZRS5/5/ Several things to note: - Running this makes my Mac OSX CPU (firefox app) jump to around 30-60% usage. - To further increase CPU usage you can click the button to generate some additional elements under the GIF. This will get you to 100%. For some reason having additional elements on the screens seems to increase the problem. If you hide the GIF, or change the .table-cell element to another display type, your CPU usage will drop immediately.