Ive read in an few articles that the use of emulating ps2 games is used under lying hardware of the ps3 and uses no software at all to emulate it. It is directly using Emotion Engine (EE) microprocessor and the Graphics Synthesizer (GS) to emulate all its compatable ps2 games.
Ive found and attached some schematics (Paul Zimmons power point presentation) along with an older patent of the ps3 in a which ive looked at breifly may be able to help out to better understand how the ps2 works and maybe how to emulate it more efficently. Also included an article by Eddie Edwards In his article he mentions a more what seems to be a more recent patent thats more through but i have yet to find it. He used to work for sony when ps2 was being developed and some of his theorys and stuff on the ps3..
Hope it helps,
Jeremy