Honestly, something is up with your system if that is a regular occurrence in Firefox. Try doing a full reset, delete all your configs and extensions. Then run

Honestly, something is up with your system if that is a regular occurrence in Firefox. Try doing a full reset, delete all your configs and extensions. Then run plain Firefox with no extensions for a while, and see if that behaves well. If not, something serious is up and you should try reporting it to the Firefox bugzilla if you can repeat it. If that works fine, something was up in your config, or extensions. Once I found someone had gone into the internal Firefox config settings and changes something years ago, forgotten it, and it was now causing serious performance problems.