Would you add this information to your report please https://github.com/ValveSoftware/steam-for-linux#reporting-issues
A slowdown for an unknown reason after same random period isn't going to be easy to diagnose. I don't know of any logs that would provide a simple answer.
If you disable the overlay does that change anything?
Truly apologize for leaving this hanging. Further testing led me to take a hopefully fairly accurate estimation of fglrx being the culprit here, which does not seem like a thing one can do much about. Closing this now; if the issue persists on more up-to-date setups, I'm sure I or someone else will submit another issue.
Nothing extracted yet.
Every now and then, game performance (frames per second; overall responsiveness) severely worsens. Through trial-and-error I've found that restarting Steam client and running the game again makes the performance return to normal. I'm using Ubuntu & Catalyst/fglrx drivers; details below.
System: OS: Ubuntu 12.04.3 x64 // GPU drivers: fglrx 2:12.104-0ubuntu0.0.1 (12.10 presumably; this is the version provided by Ubuntu, though Steam detects it is out of date) // Xorg: 1:7.6+12ubuntu2 // Desktop environment or VM: Awesome 3.4.11 (because performance suffers even more under Unity) // Steam: latest beta release.
Games run: FEZ, Super Meat Boy. Both run with enabled overlay.
If someone else is experiencing the same, are there any workarounds to this - if not, are there any logs I can provide to identify the cause?