Mastodawn

Under Proton 8.0 presets (DirectX11 renderer):

Ultra -> ~50FPS average, 100% GPU usage, 40% CPU, 70°C
High -> ~60FPS average, 90% GPU usage, 30% CPU, 55°C (When uncapped ~70FPS average)
Medium -> ~60FPS average, 50% GPU usage, 25% CPU, 55°C (When uncapped ~120FPS average)
Low -> ~60FPS average, 20% GPU usage, 20% CPU, 40°C (When uncapped ~160FPS average)

Yeah, looks like the official Linux build of the game is not as optimized as I tought.

The Linux build uses OpenGL so its slow. The windows version through proton will use Vulkan which is much faster.

The fact that it’s OpenGL matters little. It is a misconception that Vulkan is faster. But in this case, their implementation does seem slower.

Isn’t it true specifically on Windows, because the Windows implementation of OpenGL is lacking, but false on Linux?

Windows integrates only very early versions of OpenGL. Any modern release is implemented by the driver of your 3D accellerator/video card.

OpenGL on Windows has always been kinda of a disaster, DirectX support being more developed is night and day.