i talked with LDchen about this problem, and it's possible that Chronos Cross still need something that has been removed (busy bit Fix), because he thought it wasn't more necessary with last changes on core. He's investigating actually.
On my side, i have Updated FPse with Last version of SDK (4.0.3), and it seems to work better now, (yes still compatible with 2.1 and up. previously was using 2.2 sdk)
I have added a new option from Video menu to for 2D GPU acceleration for software mode, it seems to gives a small boost, and on My device, the Screen Filtering do not slowdown so much than without this option Set.
i'm currently adding USB/BT Joystick Center analog Stick support, which work on ANdroid > 3.1, but a very good software which let you use any USB or BT Pad, without rooting your phone. I asked to author if he could support phone resolution, because actually it's limited to 1024x600 or more, but while SGII and many other will update to ICS, i think this software will be very interresting.