I may have found a fix.

For me, Twitch was using about 30% of my CPU per screen. I'm not going to go into detail or lay out my specs but I did find a way to fix my problem.

1. Make sure hardware acceleration is enabled or this won't work
   (If you can't find hardware acc, go here opera://settings and type in "hardware acceleration")
2. Go to opera://flags/#ignore-gpu-blocklist
   Enable that setting, relaunch and you should be good.

I think someone above already answered this but I was unable to find this setting using their instructions.

I really hope this helps cause I've been having to stress over this for about 2 weeks and it feels good to be back at minimal CPU usage.