My computer (pc-windows 10) keeps freezing. Today, when this happened I launched Task Manager and discovered Firefox had opened 68 instances (I had one window open) and was using up 100% of my Core i7 CPU. I was on YouTube at the time.

I'd like to stay with Firefox as I have been using it for years, but this is happening all too often. Is there a way to limit the number of instances that it will generate?