@ greenmedic88
So either it's easier for the engine to run on the PS3 architecture (it would be a first)
Not a first, for example the Killzone 2 engine is far more suitable for the PS3 architecture.
or a "great" deal more time and effort has been put into the pre-code to see the better results currently seen (seems doubtful).
Well I think the game engine is more optimised for the 360, due to more similarities with the PC and being less complex.
However the Crytek game engine was designed with multi-core PCs in mind, it is and has for a long time been far ahead of competitors technically in this regard. I think due to being well multi-threaded it's well suited for the PS3 architecture (structurely) and thus runs better despite being less optimised (getting the most out of) for the hardware.
Most of the PS3 related R&D should benefit the 360 as well, but the PS3 just provides more powerful processors (3 core architecture vs 8 processor CPU architecture).