Go to settings, then look around (I forgot which panels had the sizes) and uncheck the other 1.5x, 2x, 3x graphics.Then go to debug>game>cleanup unused files.Hope this helps.
Like VoidShare said, disable all the other scales. But you have to keep in mind that this can limit your game to work smoothly on older, not so fast models as the 4x scale graphics will chew up the memory of old devices like as if it was nothing.