Macworld Lab speed tests the mid-2011 iMacs - Computerworld

Macworld - We've already shared the results of our benchmark tests for the $1999 27-inch 3.1GHz Core i5 iMac, one of four new iMac configurations released by Apple this week. We've had the chance to finish testing the remaining three
standard-configuration models, with our results showing a significant
boost for the new iMacs over the models they replace. However, not much
differentiates the performance of the four new iMacs among each other.