Was it one of the first retina 13" models? I've tried one of those in the store when they were just released, and I have to admit the scrolling performance was terrible. If you put it next to a much lower-specced, much older, much cheaper MacBook Air, it appeared as if the MBP was the weaker one of the two laptops. Very unlike Apple to release the machine the way it was.

They did improve graphics performance a lot through software updates, and the generations after the first 13" retina MBP are supposedly a lot better still... That said, I'm holding off upgrading my 2010 MBA until Broadwell which will have an even better IGP...