Hmm my friend bought S3 just 2 days back temple run is just as smooth as on iphone 4S it's basically locked 60FPS and due to the screen size it's certainly the best temple run experience I have had.Having used S3 for a while which my cousin bought... This time I feel S3 dominates One X... But his Experience after using an iPhone 4 was that S3 is Laggy and When he played Temple RUN on my Xperia Ray he said its not as smooth on his S3...
But S2 was never better than Sensation...:lips:
I must say though that the S3 has surprisingly low amount of free ram it was about 250MB on a fresh phone and once you install basic apps like facebook whatsapp etc you are left with even less. The home launcher and widgets can frequently refresh after exiting an app gotta say that was a bit disappointing. There is so much bloatware in S3 it really takes alot of resources. But then again HTC sense isnt halka either when it comes to bloatware. ^_^
Your friend probably has way too many things running in background it's just something you gotta manage in android no matter what the phone.