The glitch manifests itself during repeated, rapid diagonal swiping. When two iPhone 4s units and two iPhone 5 units, one of each running iOS 6 and iOS 6.01 are being tested side by side, repeated diagonal swiping on the iPhone 4S causes no issues, while on both iPhone 5s, the screen lags intermittently before freezing altogether.
It is not hard to see how the issue fell through the quality control cracks. Diagonal swiping is not something that occurs through regular use, but a problem users will encounter while playing specific games: the most obvious being Fruit Ninja.
If iPhone 4S units running the same versions of iOS are unaffected, it tends to suggest that the problem is hardware related. It remains to be seen whether the issue is something that iPhone 5 owners are going to have to live with, or whether it’s something Apple will patch with a firmware update.