The thing is i play a lot on my PC and this never happend in any other game (including your other games). Even games like Cyberpunk 2077 work without a struggle. I ran a few tests earlyer to see if any hardwear, video card or graphic card problems show while i played again but nothing. I had the same problem with the demo on my old PC too.
Okay, I asked around about this problem. Let's see!
1. Does it happen only in full-screen mode? If that's the case, it can be that another Windows process is interfering, like the notifications system.
2. Open the game and then click on Shift + G. It will open the following menu:
Try another option for your renderer: that should solve performance issues. Renpy games choose OpenGL first if it's available, so that could be the option that it's giving you issues.
I hope this helps!