I actually wanted to finally ask that as well.
Yeah, I played few games right before the patch - everything was fine. I updated and suddenly CPU usage is as high as Red Dead 2 and ffs works ten times as bad! I can run CP2077, RDR2 on highest details and have 60FPS and in Hearthstone I have like 10FPS... in main menu! WTF Blizzard? No, seriously, how hard it is to optimize game like this?