Same here after upgrading from Catalina to Big Sur 11.3.
Streaming videos lagging, Youtube, Apple TV app, Vimeo unwatchable. And if I switch resolution from Default to max, all windows start lagging, Finder, menus, apps, scrolling and typing text. I mean WTF??
I always wait at least few months till they catch out all the bugs, but now it is almost next WWDC around the corner and I get unusable OS that converts my $4000 mac into a two decades old Acer??
iMac (Retina 5K, 27-inch, 2020)
3,8 GHz 8-Core Intel Core i7
96 GB 2400 MHz DDR4
AMD Radeon Pro 5700 8 GB
tinybear
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