Please do work on the performance issues some of us are experiencing.
Rhino was always a very fast piece of software, using the system resources it was running on very intelligently. Please try to maintain as you update the software also in v6.
Where the performance is really lacking:
scrolling, opening and closing views, open named view panel, changing display modes, texturizing a geometry. Most of that feels and is in fact much slower on v6 than in v5.
Important: please also make sure that opening a dwg is painless and fast, even if it is a compicated and large file. Most of our manufacturers here in Italy send us dwgs which we use as references to our 3d designs. They also send us technical details, floor plans, sections ecc. - all in dwg, which I have to say is the best exchange file method for 2d technical drawings.
We also do our architectual and design drawings (talking about 2d) mostly in Rhinoceros, which saves us time and we do not need and want to use another software for only 2d drawing.