Yes. That was one of them. I saw something else by another dev who also reported the same thing.
I think the future is going to be very bright for SteamOS. Over time, the kernel and drivers will improve and devs will be getting extremely good performance from your hardware without the bloat of Window.
Hopefully it will be massively successful and MS will once again realise that they had a golden opportunity to provide a low resource thin API gaming OS but couldn't be bothered.
I can't wait to see how this ride will turn out.
Again, this is absolutely and entirely false. There's nothing about GNU/Linux (with X11, etc.) that offers a lighter/thinner/more optimized gaming environment. Windows has extremely low overhead as it is; features and software support are not bloat, at least not in the way that you imagine.
Of course a game engine that's rewritten for modern hardware and modern graphics APIs in 2013 is going to perform better than an aged engine from 2004. That has nothing to do with the OS.
SteamOS is Debian with the UI locked down. The performance is going to be the same as Debian with Steam, which has been available forever. There have been numerous benchmarks. It doesn't perform any better than Windows (some tests are about on par, some are appreciably worse).
There's nothing magical here with regards to performance.