New iteration of MacOS (Tahoe) significantly slows down older macs. I have an M1 Air and it is now very slow.
The fix is to disable Glass. In a terminal:
defaults write -g com.apple.SwiftUI.DisableSolarium -bool YES
This gets rid of the slow animations, inconsistent window cornering, and other annoyances.
Then do this so that menus aren’t transparent and unreadable:
System Settings > Accessibility > Display > Reduce Transparency
If for some reason you ever want to sacrifice performance and get the glass desktop back, you change the YES to NO in the Terminal command.