The September 2009 PC World magazine reviews the new Apple 13-inch MacBook Pro A1278 on page 54:
“In MacWorld testing, the 2.53GHz version proved to be just over 12 percent faster overall than the 2.26GHz version.”
The coincidence is nothing short of utterly astounding. In a simple and repeatable Summitlake.com test, the number 2.53 was also found, every time, to be almost exactly 12 percent greater than the number 2.26.
Despite the almost inexplicable coincidence in the speed metrics, Apple seems to have offered a lot more laptop for less money. You can also read the entire review online.