PPSSPP problems

[fabio87a]

Hi everyone!
I just downloaded the android version, have been using the win version before with no problems.
The problem is that it lags a LOT and i wonder if there's something wrong with the settings, because my device is not exactly top notch but is not that bad either, especially if compared to the previous gen models.
I have a Xiaomi Redmi 1S, with snapdragon 400 quadcore clocked at 1.6 GHz and adreno 305 GPU (updated to last FW), all the other native android games (Dead trigger, zenonia, etc) work well.
I tried a few games (FF Dissidia 12, Ratchet and clank, FF7 crisis core, GoW Chains of olympus), and they lag so much they can't be played at all.
Is there anyone that can help me with system settings to smooth the gameplay? Is anyone here using my same device or a similar one (Moto G, LG G2 mini or other snapdragon 400)?

ty in advance

EDIT

I followed this guide (http://forums.ppsspp.org/showthread.php?tid=5352) and changed 2 values as advised for android users
1) BUFFERED RENDERING -> NON BUFFERED RENDERING
2) CHANGE CPU CLOCK 0 -> 60

the games are playable now, altough still not satisfactory, in some situations there are graphics anomalies (the screen goes black or there are red lines on the screen borders) but acceptable.
what else can i change?