All of this "game mode" talk has me feeling a bit nostalgic for Windows XP, and setting up a separate Hardware Profile to boot into that doing away with all unnecessary services and hardware devices. I want to believe it made a difference back in the day.
"UWP" games do not equal games purchased through the Windows Store. That might be the only place to get one currently though. If its beneficial, and the future, then it stands to reason to put the most effort there. Older games will inevitably run much better on up to date hardware anyway.
I feel like the inconsistency and quality issues between a win32 and UWP version of the very same game might make this difficult to test. Would 4 versions of "Rise of the Tomb Raider" (win32 dx11, win32 dx12, uwp dx11, uwp dx12) benchmarked even produce usable results?
Looking forward to seeing the benchmarks.