I've been enabling Rhino version 5 light weight extrusions to the Geometry Gym Rhino plugins, that uses less memory, meshes faster and saves out to much smaller file sizes.
I've seen and heard some positive demonstrations and reports of this improvement, but decided to do some quick bench marking for myself and the results are impressive.
I prepared some approximate models of the British Museum Great Court Roof as part of this discussion with importing IFC models into Archicad.
The model comprises 5180 members, and the improvements from v4 to v5 are really impressive.
I've benchmarked using the Geometry Gym IFC importing plugin, which will use the new extrusions when running in v5. If you want to try for yourself, install/update the plugin, http://www.geometrygym.com/downloads and the IFC data file can be downloaded here.
Or, if you just want to open the rhino model, download here.
Time wise (only considering the generation of the extrusions, ignoring file reading time etc) it took 35 seconds on my computer to generate 5180 version 4 extrusions. In version 5, it took less than a second.
When saving out the rhino model, version 4 produced a file 74 MB, version 5 produced a 3 MB file.
And there is very little lag or delay when panning, zooming and rotating the v5 model, in comparison with v4.
The only drawback (which should be a temporary matter and improved as the beta version of 5 progresses) is a much slower start up time for version 5, particularly 64 bit (which seems to be made slower by loading geometry gym plugins which is being investigated).
However, if you're working on skeletal or frame models, I strongly recommend taking the step up and using v5. Extrusion elements also can accomodate end miter planes, which I'm in progress of enabling to the plugins.
With regards to the IFC plugin, you might also notice some other speed improvements when importing large faceted brep models generated by other BIM software.
Feel free to comment with any suggestions or observations of your own.