FWIW, I have been using Mac for Rhino for a few months now, on my 3 year old 13" MacBook Air with Yosemite, only 4 gig of memory, without any problem. I get a rare “wheel of death” moment that probably has more to do with other programs in the background than Rhino. I have been blown out a few times when I did something to push the program.
I think Mac Rhino its pretty cool for us hobbyists. There is still some cursor inconsistency (sometimes I have an arrow instead of crosshairs), and Zoom/Window works on the second effort each time you type it (never the first), and you have to type ZW when you are using the Mac Theme as the Mac style command window hides those icons during execution of any command. I am pretty old and have a pretty small screen and pretty big bifocals so I need to zoom in to get the right snap more than most I think.
But I only do small hobby projects, sailboats, toys, mining equipment (retired mine super), and I am comparing it to Sketchup 2015, the object being, “Do I move up to Sketchup Pro or buy Mac Rhino?” To me, Rhino is more in line with the skills I used in AutoCAD years ago, so the learning curve has been gentle. I don’t miss that “stickiness” where if you fail to group just one time…, but the Push/Pull of Sketchup is great and I would love it if the gumball was developed even further to help… Frankly, I almost dropped my Sketchup Icon from the dock today, seldom use it now. (I still grab stuff from their library though! It re-works pretty simply in Rhino.)
My Magic Mouse works great with Mac Rhino, but as with other Mac programs you have to kick-start it once in awhile with the touchpad. Maybe that is just a MacBook Air thing…
As for lag, lag seems to me as an inherent problem when you manipulate huge models or drawings and >50 meg to me is huge. I learned Cad in the 90’s, back then we had to use small files that were later assembled into large reference files for output. I still keep my files pretty small, so perhaps there is a lag, just not affecting the way I draw on my little Mac - and I love my little coffeeshop Mac in a Sack.
I will be buying Rhino, going to give it some time though to see if folks will do some plugins for it this summer, and maybe some improved render program will come available, or at least some better tutorials for Rhino Render. Perhaps they are out there and I just haven’t found them.