Certain websites cause Firefox to continuously use 100% CPU. Some of them I can just block and never visit, of course, but some others I unfortunately need to use sometimes.
But how do I do this? Firefox DevTools have a performance inspector, but it seems to only record frame rendering times, response time, etc, I couldn't find information about where real CPU time is spent, and it is also limited to single tab, as far as I could tell.
I tried disabling all extensions and it showed that they do not cause 100% CPU usage.