Mine seems to have the ATmega64-16AU and a 20MHz crystal.
Most components can tolerate a slight overclock, but who knows.
I suppose you could try to use a native 20MHz part and see if it works better 
Mine seems to have the ATmega64-16AU and a 20MHz crystal.
Most components can tolerate a slight overclock, but who knows.
I suppose you could try to use a native 20MHz part and see if it works better