John Carmack told Edge that the PlayStation 3 does lag a little bit behind in terms of getting the performance out of it. The Xbox 360 version of Rage matches the PC's 60FPS, while the PS3's framerate currently runs at just 20-30FPS.
“The rasteriser is just a little bit slower – no two ways about that. The RSX is slower than what we have in the 360. Processing wise, the main CPU is about the same, but the 360 makes it easier to split things off, and that’s where a lot of the work has been, splitting it all into jobs on the PS3.”
He is, however, confident that the PS3 version will match that of all other supported platforms: “Everything is designed as a 60 hertz game. We expect this to be 60 hertz on every supported platform.”