Strange behaviour with buffered rendering

[JumperTwo]

while testing my games (for example MotoGp) , i noticed that with buffered rendering enabled (and of course JIT and fastmem) i only got a very little speedboost and this is strange because i got a relative powerful phone, an xperia s with a 1.5 ghz Scorpion and Adreno 220, that should be at least on par with a 1.2 ghz cortex-A9 (in theory 5% more faster).i already have seen videos of many 1.0 ghz A9 (with slower gpu) devices hitting much more speed than me. the curious thing is that if i disable buffered rendering , i got full speed on all my games (but emulation's window only cover 1/4 of the screen) could be a problem with Adreno driver?

i run last nighty ppsspp (3ff46cff05) on gingerbread (stock).