“Which is a long way of saying that everything on iOS is drawn using OpenGL. This is why animation on iOS is so hopelessly fast. You may have noticed that -drawRect is not called for each frame of an animation. It’s called once, then you draw your lines and circles and text onto an OpenGL surface (which you didn’t even realize), then Core Animation moves these surfaces around like pulling on the strings of a marionette. All the final compositing for each frame is done in hardware by the GPU.
Android seems to have made the decision early on that they wouldn’t force their manufacturing partners to include a GPU. This decision made total sense back in the pre-iPhone days, but now it’s causing pain, as even the new hardware acceleration in Android 3.0 is limited by the original software-based compositing system.”