I dunno, this morning I was able to get minecraft, sims 3 (via wine) and steam (playing xcom) on an Arch/BridgeLinux liveUSB playing without issues in about 45 minutes. Kernel 3.12.x means the 3d was slower than I'd want (AMD free drivers are waaay faster in the new kernels), but I didn't want to do a full pacman -Syu on the liveUSB. Performance was decent, and had I installed to hard drive, would've been competitive with windows even without the catalyst drivers installed (which is a yaourt install away).