Share your system info in the post, don’t ask people to go dig for info, especially as these info are not fixed in time and will not be relevant later.
Also, natively it probably runs on OpenGL, and Windows version on DirectX (which will then be ‘translated’ with WINED3D for DX9-10-11 → OpenGL, with DXVK for DX11 → Vulkan and VKD3D for DX12 → Vulkan).
On my experience games run often better on Proton with DXVK (sometime VKD3D) with shader pre-cache enabled in Steam), as Linux version are often bad ports, or ports that didn’t receive lot of attention to issues.