Are the performance problems you refer to the horrible slow-down in multiplayer? I've never had any client-side performance problems with AoC (Steam edition or prior), but the network slow-down has always been there, and makes substantial games with more than about 4 players essentially unplayable. I haven't checked on the Steam edition since a couple months after its release, but if they managed to fix that I would be elated.
Both client and network but most of the fps issues and scrolling issues have been fixed. I think patch 3.8 fixed some of the memory leaks and "out of syncs" also. It's definitely worth another go. They also changed the default hot keys to a grid layout late last year too, just in case! :)
