Looks like there is no real difference according to system-monitor - a before and after.
Actually there is a slight difference when not using lightdm. Why. I don't know. I assume it may be that lightdm is TSR and is hooked to the desktop , or, just perhaps with Unity and not other DEs
At this point I can't really document that Unity *is* actually faster but it appears this way just from response times. I also have another 13.04 install on the same machine with same conditions so my initial post was about the daily image of that day, Friday, and how Unity jumped off the page using the live USB and then subsequently the hard install.