It involves Final Fantasy III and is kinda minor. If you aren't interested, don't open the spoiler.
There's loading time in Final Fantasy III for the PSP. Y'know, walk out of a building, wait a while, now you're outside of the building. Unfortunately, it takes a while. Long enough to get a animation for it...which probably doesn't help.
The problem is this: The DS version doesn't have it. At least, not as long, anyway.
This means one of two things:
1) Discs really don't work for handhelds or
2) The PSP has worse engine power (or whatever puts the graphics up) then the DS.
Which means it has worse engine power then the Wii.