If no one answers soon, then someone who may know is Aquas (SRC@Aquas, Twitter@Aqy). He runs Ultimate Ghouls n Ghosts on PStv, so he's familiar with the hardware.

PSP is still faster for PS1 games if I remember correctly. The order (at least for Crash games which I know about) for loads is: PSP (Fast Disc Speed) -> PS2 (Fast Disc Speed) -> PSTV/PS3/PS4 (No Fast Disc speed available) -> PS1.

I could be wrong however and it might be game dependant.

Funny enough though PSTV is faster for PSP games then PSP.