"Nope. I watch a lotta youtube on a PC, FF runs vids like crap because Google changes something, and FF struggls to play well unlike Chrome or Edge."

You must have a hardware problem, as I'm playing 4K videos on a 1st-gen Ryzen and GTX 1080 using Firefox and I've never had a single issue since I got the machine, around the 4th week the processor was available to purchase.