Hello, This has been a problem every since the Firefox Quantum update, but I never asked about it. My issue basically is that when I wake my iMac from sleep, Firefox decided to use 400% of my CPU (each core = 100%), and the Mac becomes unresponsive from a second to a few minutes at worst. Generally, the longer my computer is in sleep mode for, the longer it takes for the Firefox CPU usage to die down. Is anyone else having this problem? Thanks!