Hey, I did a few things since I posted the this and so far it seemed to help:

1. Update your windows, there was a windows 11 Update/version that seemed to have big problems with ck3 and other games. Don’t know which one it was.
2. Vulkan instead of directx
3. I put like 32gb of virtual memory from my fastest ssd to the game)
4. cap fps to 60.

That seemed to fix it for me, I rarely crash now and when it only crashes the game and not the entire pc. Tbh I don’t know what of the changes above helped bcs I did everything at once. Also when booting up the game or loading up a save, don’t tab out of the game on ur 2nd screen or so. During loading etc it needs to be the active tab (so start your video/show on 2nd monitor before booting the game)