Having endured this problem for some time, I finally booted FF75 (previous versions had this as well) into safe mode and tested FF for two days with no problem. Began reactivating my add-ons one by one and running them for two days before adding another. HTTPS, when added, preformed properly for about 15-20 minutes and then the CPU percentage spiked to 90% plus and would not drop. Restarting FF said it was still running. FF continues to run even though it has been shut down. The process has to be killed before FF will restart. The rogue process will run indefinitely if it is not killed. Seems only to happen if HTTPS Everywhere is activated. I have tested add-ons one at a time with no others active. This is the only one that causes this behavior. I really like that add-on but find its use prohibitive due to this problem. There is no place on the add-on website to report this. Should it be reported as a bug and, if so, where? Thanks in advance for any assistance on this issue. I doubt I'm the only one who has it.