If you are experiecing immediate crash upon starting the game (game window flashes for a fraction of a second) there is a workaround where you disable D3D9 vulkan and use standard WINE D3D9 OpenGL by adding the PROTON_USE_WINED3D=1 environement variable to the command line options. (See above for an example command line with extra options that may improve compatibility/performance)

Tested on the example big city. (Keep in mind I'm using intel integrated graphics, 4th gen Haswell), ran smoothly when not moving around. Simulation speed seems ok and constant. Moving around is a bit stuttery, specially on farther zooms. Setting shadows to medium also seem to improve perf a bit.