I've used Firefox for years, without problems. Now it's turned into a dreadful resources hog - frequently 100% CPU and Disk use, and at least 70% of the memory. Sometimes I can't even type the laptop is running so slowly :(
I've googled, and one piece of advice helped a bit - to type about:memory into the address bar, then choose 'minimize memory usage'. But only a bit. It's still a hog.
Has anyone found a way to sort this, or will I have to delete Firefox and use Chrome instead? :(