3d mobile game (android) optimization !

Difficult to answer such a general question... but here goes... some devices just run at 30fps, so first off, try to get a couple of different android devices. maybe from ebay, some newer, some older. Make sure you are building with all your logs disabled.... logs are slow..... make a build rendering nothing, check your fps for that. ( not.... don't show your fps via logs to debug .log , show it on screen as a number ) Read some unity optimization docs online, and in the unity documentation. e.g. here. and here. personal tip :- over-draw view in scene view window is your friend on mobile. over-draw is when the graphics needs to draw on top of itself many times in one frame, basically wasting its time rendering things that are not seen. Plan accordingly... ! Just say to yourself... my device may only be able to render 1 to 1.5 screen's worth of pixels per frame, ( it may be more or less depending on hardware) then you'll see what I mean.