At work today, I didn't realise just how bloated my Firefox profile got until I tried playing a YouTube clip and it kept flickering and stuttering, whereas Chrome would play it fine.
Upon checking Task Manager, it was clear something was hogging the CPU. Sure enough it was Firefox as the CPU usage went to near zero when I closed it. However, as soon as I opened Firefox, it started hogging about 50% CPU usage non-stop just left idle on its homepage:
I did notice my PC running slower than usual recently and indeed this was the culprit as usually I minimise Firefox, not realising it was lately taking up half my CPU usage.
So I figured it was time to clear its profile and indeed the local Firefox profile was pretty large:
It's also worth noting that this is after running CCleaner, so while it does a pretty good job at clearing Internet Explorer's cache, it seems to leave a lot behind with Firefox.
So for curiosity, I just renamed this one folder (steps 4 & 5 in post #1) and opened up Firefox. What a difference...
Unfortunately, this didn't solve the issue I'm having with YouTube as the video still keeps flickering back and forth between frames, even though YouTube plays fine on Internet Explorer and Chrome.
On the other hand, renaming (or deleting) that one Firefox folder doesn't wipe cookies, URL history, bookmarks, etc. so can be a handy way of speeding up Firefox without a total profile clear out.