Even if it's bigger over the wire, they might still save on total rendering time and/or battery life.
They seem to be suggesting that these optimisations are intelligent and vary with circumstances, so they don't have to work every time as long as they can predict when the right time to turn them on is.
They seem to be suggesting that these optimisations are intelligent and vary with circumstances, so they don't have to work every time as long as they can predict when the right time to turn them on is.