435.21 driver is quite old now and Nvidia has had vulkan changes / fixes added in since then. This game is dx7/dx9 and so if its using dx9 then its using DXVK/D9VK aka Vulkan unless it gets disabled.
Personally, I would recommend updating the driver to the latest and maybe also trying Nvidia's vulkan dev driver.
Also double check against opengl performance "PROTON_USE_WINED3D=1 %command%".
Well I upgraded to 440.64 then tried again. No differences. Then I tried all of the usual launch options again. Still no differences.
There's some interesting results going on here. The stuttering happens when I run it with Proton and when I run it with wine. However, the problem is completely fixed when I run it with winefile. Keep in mind this is when all 3 are using the exact same prefix. I can't figure out why it's like that.
Compatibility Report
System Information
I confirm:
steam-277110.log
Symptoms
Everything seems to run fine, except for 2 things. The framerate is crappy (about 11-25 fps) and, what's much worse, there is MASSIVE stuttering when the mouse changes directions. A low framerate is tolerable but the stuttering makes it very hard to play.
No launch option really made any kind of difference. I tried it in fullscreen, and windows mode. I tried with software and hardware rendering. Nothing helped.
Reproduction
Run the game and move the mouse back and forth. Watch the framerate and compare that to not moving the mouse at all.