I've been experiencing the same. And experiencing stutters/lag on the 19' MacBook Pro 2.4Ghz i9 with 32GB .. So it's plaguing even the top-tier rig. I sent in a log to Apple, but basically there are stutters/lag whenever inputting text.. Like right now as I type this. And as the others have said when resizing windows.. It's not inhibiting me coding, but it's making it VERY frustrating.. especially after shelling out nearly 4k for this thing. I love the look and feel of Big Sur though so hopefully they can get this sorted out. I know developers can't snap a solution into existence, but some acknowledgement of working on the problem from Apple would be great.