I also believe that for some time now, as the focus is on 3D graphics, GPUs are comparitively getting slower at 2D than 3D, meaning it may even be possible that a 3D sprite-based UI system may be more efficient than a 2D image-based one.
Regardless, you're talking thousandTHs of millisecs here, so it's really not an issue.
Regardless, you're talking thousandTHs of millisecs here, so it's really not an issue.