While they are wrong, in that Proton is absolutely a subset of Windows APIs, it is describing aiming for an implementation detail.

Yes call X is faster than call Y in Proton, but that could also be because its only 50% written and skips a bunch of side effects that will be created after you have written your game.

Therefore you need to view Proton as a potential moving target. Not that Windows isn't too, but its just not as clear cut as is being claimed.

I know this because I pin some games against older versions of Proton because they work better/faster.

Thank you. I didn't do a very good job of explaining why I think Proton is worth targeting specifically if perf tests show it running faster than Windows.

The Windows API perf topology is astronomically large.

That Proton is faster than Windows can't be universally true, but if you stick to that subset that has good conformance with Windows APIs and is also faster, that should be the target (and everything is moving of course).

Cross benchmarking games between Windows and Proton, taking API traces and finding those subsets of APIs can usage styles will enable a game developer to target those Proton APIs that are both conformant and fast. It is that subset of Windows APIs (temporal spatial structural usage) that I am suggesting being the target. The API linting tool might itself compare API traces. In fact for those API traces from performant AAA games, I could see generating a header file that only exposes the same API as used by that game.