SRB2 is WAY different to any other PSP game, and while the code DOES need optimisation and some modification, technically in its current state it should at least start, which the current port does.
The PSP probably has enough power for an optimised SRB2, so far in this topic some people think clock speed makes a CPU. I'm going to tell you now: It doesn't. AMD proved this years ago with their Athlon XP.
You don't need to rewrite the SRB2 engine for the PSP version to run, that's preposterous, if we had to do that, there WOULDN'T BE a PSP version. There's one reason Sonic Team Jr. coded SRB2 in C, you know: portability. They wouldn't use Assembly or Visual Basic for this, because that would make SRB2 practically impossible to port to other architectures (Assembly) or anything other than Windows (VB). C can be ported to other architectures and operating systems easily.
Anyway, I think I'll stop my rantings now...