Firefox recently started to constantly freeze

Starting about a week ago, Firefox has had periods where it would freeze for about 5 seconds, followed by working normally for about 10 seconds. In between cycles of freezing, there would also be periods where it functioned normally. The freezing doesn't seem to be triggered by anything specific. It happens when I'm scrolling, typing, or even sometimes when I'm doing nothing at all on a page. This also happens whether or not I have other programs open that could be slowing things down. According to task manager, I have plenty of spare CPU and RAM when it happens. I've tried turning off hardware acceleration, recreating the places file, and checking session restore as per [[Firefox hangs or is not responding - How to fix|this help article]]. It has also happened after restarting Firefox, so it shouldn't be a problem with that.