I'm on an M4 Pro MacBook-- basically the fastest computer you could buy from Apple before today-- and opening/closing the tab sidebar in Safari on Tahoe takes multiple seconds, even if I have only 4-6 tabs open, and seems to drop to 5 FPS. It's comically bad.

It's so bad I switched back to Chrome. I had thought Chrome had a major battery life penalty compared to Safari on Macs, but I checked more up-to-date info and apparently that's outdated.