If this emulator is based entirely on mupen, it is almost guaranteed to be slow...it doesn't even work properly on computers, I personally hate that emulator. Unless someone creates/editys an amazing dynarec recompiler like youngzh. There is no way i see this emulator as being able to move full speed on xperia play devices...
Also, on a side note, why does no one include sound compression in emulators like these. Sound compression goes a long way in increasing emulation speed. Just burns me every time the option isn't included in emulators. :/