Severe and "permanent" FPS drops on beefy PC

Fixed - installed older Nvidia drivers - version 566.14 - played for a few hours without issues

Hi! For a few last days I have a very weird problem with Snowrunner. I have a beefy PC (Ryzen 7800X3D, GeForce RTX 3060, 32GB RAM), and the game works flawlessly... for a while.

After playing for some time, my FPS severely drop to 14-15, and they stay like that until I restart my PC. Restarting just snowrunner isn't helping - I have low fps even in main menu.

What's even more strange, is when I deactivate snowrunner window (I have 2 monitors), so it runs "in background" I instantly get 60 FPS back. Activating snowrunner window makes it drop to 15 again.

Changing video settings doesn't make any difference.
I've tried turning on and off V-sync, frame cap, background frame cap, changing resolution, settings to low, so on and so on...

Haven't found anyone with similar problem as I do, can anyone help?

PS: I'm not using any mods.