DISconnect the network to be specific.
During a recent session the conversation turned to the excessive amount of time it takes to export a 3D view to dwg so the Revit model could be used in Autodesk Viz or Max. This prompted a little experiment. Set up a 3D view of a model, export to dwg, took several minutes to complete. Do the same thing but this time remove the network cable (from your PC) before running the export, took several SECONDS instead.
Some anecdotal evidence suggests that having a network share of resources for Revit can contribute to this, such as the material libraries. As such the act of dis-connecting the network from the pc seems to resolve any such issue.
When you need to do this for a project with Worksharing enabled you might also consider using Detach From Central to isolate the work you do from the actual project.
This won't affect the export time but it will avoid having to Save To Central if you make any changes.