No, the games are all stored server-side.4.70 is what I have and it freezes like crazy. It seems most of the people in the thread who says it's running fine are using 4.73. So that is what I am going to try.
I would guess erasing it would wipe your current games, but maybe someone else can verify. One of many pains of having to sideload. You can't run a normal app update.