Well, I have to say that I am also very disappointed to hear this… as Holo said there is clearly a trend towards more detailed models and 3rd party 3d objects.
Every day I fight to find ways to organize complex scenes so that they become useable in rhino, especially at the end of a project…
In another thread I tried to approach a part of the display performance problem from another direction with a few interesting outcomes:
http://discourse.mcneel.com/t/wish-viewport-proxies-for-blocks/31428
Off course there are hundreds of tricks and workarounds (proxies, display modes tuning, meshing, layer management and so on…) but each of them makes our work a bit more complicated… you have to hide this layer before you can do this, start this macro before that…
At the end of the day display performance is very critical for a big number of projects.
At this point I would like to note that since Holo was so generous to develop the holomark tool we have at least a reference for display performance.
The bad thing however is, that holomark shows us that rhino is not very good at using the computing power of professional open gl cards at the mode the majority of users seem to use (shaded or rendered combined with lines)
I would love to hear that there is at least a strategy to address this issue in any way in a foreseeable timeframe.
by the way: I love Rhino and don’t want to work in another CAD program, 5 minutes ACAD and I am feeling sick 
, but I think it is important to discuss these issues openly.
my 2 cents
Andreas