I seem to be having problems running S4 Beta on my iMac and my MacBook Pro. Both are previous generation but with S4 I get system slowdowns and S4 hangs and crashes! 
However, I've just installed S4 on my Win XP at work and it works like a dream!! What can the problem be?!
However, I've just installed S4 on my Win XP at work and it works like a dream!! What can the problem be?!