The performance difference between logic and Cubase is somewhat dependent on what you are doing and what your workflow is. If you are working with Virtual Instruments and are playing in Live mode, Logic can initially appear much more efficient, but there is a tipping point, where everything goes horribly wrong. If you are not using live mode, Logic adds an extra buffer, so in order to get the same performance with Cubase, just increase your soundcard buffer. FWIW this is sort of what ASIO Guard is designed to do.
DG