Performance for me has been awful since a few releases ago. I have eight cores, and I often find that Firefox is using 100% of all eight cores when I'm not eve

Performance for me has been awful since a few releases ago. I have eight cores, and I often find that Firefox is using 100% of all eight cores when I'm not even using the browser. I ran perf on the processes and what it's doing is beyond me (something with futexes and the DOM). (And before anyone asks, no I have not submitted a bug report, because I don't know how to reproduce the problem. I have seen other users complaining on reddit, and I so I know I'm not the only one, and I expect a proper bug will eventually get filed by someone who knows how to diagnose and communicate this better than me. I've searched the bug tracker every few weeks and haven't seen one yet, though. It's just frustrating to have a release with so many frivolous changes when the browser's performance is already abysmal).