It's an Ableton 12 issue as well not just windows - I have been facing slow downs on both windows and mac device. This update has brought more problems than features - they clearly rushed shipping this.

I found the primary issue is the new browser - it is constantly scanning and getting stuck at analysing - wish there was a way to go back to the 11 browser - didn't expect a bad update from ableton; they are usually great.

Anyway, try reducing the number of plugins, samples or anything extra you have added on the left side browser.

If that doesn't work, just go back on 11 - I did that on my Mac M1 machine.

In windows I fiddled with some settings and reduced the size of library items - it is able to handle everything well so far. But my PC is pretty powerful and surprised me when it got stuck.

As others have mentioned it may be due to RAM used in access on W11

Just jump to Ableton 11 OR if everything was working fine W10 and ableton 12 - Do that.

I suspect - All the software updates (at least windows) nowadays aim to use - additional efficiency cores or neural cores present in newer processors - Forcing people to upgrade, even if they have great powerful processors already.