I've been testing a few games that use unity3d engine, and all of them do not run smooth.
Screen scrolling jitters in all of them.
I've tested Teslagrad, Shadowrun, Rochard, ARMA Tactics, etc.
When the same games are tested in my Ubuntu install with an openbox session (without compositor) everything runs nice and smooth.
I've also tested the same games running in Gnome3 desktop session and there's no jittering. I've had to had in /etc/environment the following line CLUTTER_PAINT=disable-clipped-redraws:disable-culling to avoid tearing, though.
I'm running a GTX680.

I've been testing a few games that use unity3d engine, and all of them do not run smooth.
Screen scrolling jitters in all of them.
I've tested Teslagrad, Shadowrun, Rochard, ARMA Tactics, etc.
When the same games are tested in my Ubuntu install with an openbox session (without compositor) everything runs nice and smooth.
I've also tested the same games running in Gnome3 desktop session and there's no jittering. I've had to had in /etc/environment the following line CLUTTER_PAINT=disable-clipped-redraws:disable-culling to avoid tearing, though.

Ok, but on my rig I get the same options.

The OS takes only about 5gb of space. The problem is that the installer is in alpha state and doesn't let you choose which hard drive you want to install nor the partitions you want to install, and won't let you create the partition size you want.
The installer just use the all disk and create the partition according to disk size.

Linux and Windows client have exactly the same options. Texture quality can be set to very high in both systems. The benchmark was run with exactly the same settings on both systems.
SteamOS is clearly slower, even Ubuntu is faster.

For curiosity I've benchmarked the performance between both OS's using a resolution of 2560x1440 8xMSAA, all settings maxed. Using a intel 4770k + GTX680 + 8GB rig.
I've reached the following numbers:

Win8.1 - 235,82fps
SteamOS - 153,65fps
Ubuntu 14.04 - 175.28 fps

I tried to apply the following Nvidia optimizations in launch options but the game refused to start. LD_PRELOAD="libpthread.so.0 libGL.so.1"__GL_THREADED_OPTIMIZATIONS=1

To simulate similar conditions I runned Steam windows client with -steamos prefix and Big picture mode.

Edit: Added Ubuntu 14.04 results.

I think you haven't opted in to beta.
Boot steamos recovery mode.
In the command line type this:
sudo apt-get install steamos-beta-repo
sudo apt-get update
sudo apt-get upgrade

After this restart your pc, and you should have the lines, and you could comment them out.

http://gtm.steamproxy.vip/groups/steamuniverse/discussions/1/648814395741989999/

Jodie & Aiden lähetti viestin:

I would like to Opt in but i have a question? If it is an OS would it delete my current OS or would create a partition on the Drive for SteamOS?

Steamos big picture have serious performance issues with Left4Dead 2. After the intro on the first level, performance drops to single digits and stay stuck there, and no matter what I do it's stuck there.
I now that it's big picture related because I have ubuntu running on another partition and big picture have the same behavior. Running in desktop mode doesn't have any issues.
I´ve seen this behavior in at least two more games, Serious Sam 3 and Metro Last Light.
Sometimes in Metro Last Light the performance tanks after the intro, in the menu selection.
In Serious Sam 3 it happens randomly in the middle of the game.
I'm running a Gtx680 with a 4770k.
Edit: After further testing I came to the conclusion that the performance issues have one cause: Incompatibility between Steam big picture and a compositor running behind it.
I've reached this conclusion by installing openbox in my ubuntu install, booting from an openbox session (which doesn have any compositor), running Steam big picture and running Left4Dead 2. Everythinh is fine now.
Ubuntu is using compiz so it's not a specific problem with Steam compositor, but an incompatibility between compositors and big picture.
I've tried to run SteamOS with compositor disabled, but surprisingly I loose the ability to navigate the menus through my keyboard (mouse works), but when I enter a game none inputs work (mouse and keyboard).
From my experience running Steam Bigpicture without any compositor give the best performance and no problems. So ditch the compositor, there's no need for it.

I've already tried that, but I loose keyboard interation in bpm and I loose mouse and keyboard in games.