I've had this problem on an Arch machine after no use and no update for a long time. Thunderbird was affected as well, and both unfreezed at the exact same mome

I've had this problem on an Arch machine after no use and no update for a long time. Thunderbird was affected as well, and both unfreezed at the exact same moment a few minutes after launching the first one. I never had time to investigate this but this was obviously a system problem, Firefox and Thunderbird are fast on all the other machines I use.