Persona 4, pretty bad FPS.

[simple]

You want a newer one than 890 or you get the lovely flashing floor bug sadly I don't remember on which revision it was fixed.

I'll attempt to mess with success and find that plugin
I'll edit this post with results...

EDIT:
DRALOR FTW!!!!

Using 890 Caused the game to slow down during many intense battles as well as graphical glitches (see: flashing floor bug mentioned above)

I step on over to the GSDx Thread and decide to download the latest plugin, and it works flawlessly! Even my framerate drops have disappeared ! I would have originally said the playability of the game for me was around 80%, but now it's definitely 100% (110%++ really, my framerate bursts so when the limiter is off!)

Thank you dralor for pointing out the flaw of 890, persona 4 is completely flawless for me (GSDx 1538 SSE41 DX10!)

[CentroX]

do you need to set the persona floor hack in p4 if you use the latest betas?

[simple]

Yes; I have it on and it doesn't seem to be doing anything negative.(i guess it's working as advertised)