How can I disable the "Welcome, Name!" banner notification for Game Center? As per this question I've found banners to cause slowdown on iOS 5, it turns out the "welcome, you have been signed in" Game Center message does this too, and on occasion it will interupt me several times in a game if I switch in/out of the app while playing as it logs be in/out repeatedly.

Is there a way to disable this notification while leaving Game Center enabled? I tried revoking the banner notification rights from Game Center but the pop up still appears.
That login banner is a provided aspect of the Game Center API in the iOS SDKs,  as far as I'm aware there is no way as a developer to disable it from opening when the Game Center login completes. As a user, there is certainly no way to disable it, because it is part of the application's compiled source code.

However, note that it's not the banner that is causing the delays and skips. It is actually the entire login process to Game Center. My only advice is when you open a game that has Game Center logins, open it up to the first functional screen, and just wait the ~5-10 seconds it takes to reveal the Game Center banner. After the banner has displayed and disappeared, proceed normally and you should not be affected any further.