But it was not clocked at that speed.
Over clocking does not give linear performance increases(law of diminishing returns kicks in) in processor performance.
Worse yet, it would result in abysmal battery life.
The Iphone 4S battery life is nothing to write home about and the current iPhone5's battery life claims are actually worse than that of the GS3.
Image
For GS3(claimed)
Talk Time 22 hours
Maximum Standby Time 800 hours
Samsung Galaxy S3 Battery Power Test
http://youtu.be/P62628a76Gc
http://www.techradar.com/reviews/phones/mobile-phones/samsung-galaxy-s3-1078667/review?artc_pg=14
Real world testing is yet to be done on the iphone5 battery claims, but my bet is on the GS3. If Apple clocked the A6 higher, the battery life would be even worse than that of the 4s.