Can you elaborate? If you are drawing to the buffers at half the rate (and correspondingly swapping them out at half the rate), how would that not be easier on the graphics processor?
Triple-buffering allows for arbitrary relative speeds. The result is, you draw to the buffer as fast as you can in total disregard of the actual refresh rate. So they're both at "100%" CPU/GPU, but that simply isn't enough for Google Maps.
I think Google actually locked Google Maps at 30fps though. In other words, I don't think it is actually drawing as fast as the processor would allow, were Google to remove that lock.
Otherwise I'd expect to see more fluctuation in the framerate of the app, especially when there isn't much detail on the screen (similar to Apple Maps, which is obviously not locked to 30fps).
