[SCdF]

You're not the only one. Valve are not the first people to port Windows games to Linux, and while some people claim they're faster, the general benchmarked consensus I've seen over the years is that both platform are, within 10% or so, basically identical.

[Periodic]

Their results are basically within 15-20%. The major achievement is just having acceptable performance. After that there tends to be so many other factors that you can tweak that only two metrics make sense: FPS and image quality without any non-automatic tweaks, and then the maximum that can be obtained by extensive optimization.

For most people, they just want the game to run such that the difference is not big enough to warrant switching OSes for gaming. For me, I just want it to be close enough that I can't be bothered to reboot.

I've been getting some great performance through wine for some games for quite a while now. Under the same settings I've occasionally had slightly better or slightly worse performance depending on the game, patch-level and settings. For me the bar is whether it is playable and looks decent at all.

[enneff]

They said that some of their optimizations applied to both Linux and Windows, bringing the final scores to 315 and 303.4 fps respectively. That's well under 10%. Seems believable to me.