Low framerate on Android devices

Well, I think, it's a very common problem. All my android devices, from old HTC to new Xperia, have surprisingly same framerate - about 18 FPS, while Apple devices, even 5th gen iPod, where Crossy Road got freezes, got stable 60 FPS.

My game is about falling into a big pipe and avoiding obstacles. No light sources, only 35-45 quads with transparent textures and 30 quads with non-transaprent textures on screen. All textures are RGBA 64x64 pixels.

First thing I thought about were shaders. I was using simple Unlit Transparent shaders, but then I made custom shader for obstacles and Unlit for walls. It made a performance boost for Apple devices but not for Android. Then I disabled Vsync and still nothing. I really don't know what to do to improve framerate on Android devices. I'm seriously thinking about skipping Android as platform and focus on Apple store. But I really don't want to do this. Do you know any way to improve this fps to at least playable 30?

P.S. Excuse me for my poor English, that's not my main language :)