It's just a heavy workload game. Not a GPU, but the CPU intensive, because of some strange VU0 programming (it is a launch game ported from the PS1 by the way). None of the holy trinity hacks do work (0x21, 0x41 and 0x46). But you can speed up a bit by setting the NO-IPU Custom to a high negative value (something about -30000). Anyway, there is a HD port on the PS3 though.
I encourage you all to edit the compatibility list. Improve it by gathering as much information as possible. It would help everyone.