Trimmed surface performance

I am trying to performance tune a CAD application. Here are my starting questions:

1 We have several tesselation options, use the ParaSolid (OEM Library) functions, the NLIB NURBS library, or OGL. We are currently using ParaSolid and pushing tri strips into OGL. In terms of RAW speed on multiple Win 2000/NT platforms, is there a preferred option for highly perforated surfaces (lots of circular holes).

2 Specifically, if we push trimmed NURBS into OGL via GLU, when is tesselation performed. I know the answer will hardware dependent, give me some idea of what the spectrum of answers is.

3 We frequently have large continuous surfaces with fine detail, engineers are like that. Depending on view angle these fine details may or may not be in the rendered field. With our current solution we have to assume that they are always in the field because the user may rotate them into view. Does the OGL tesselator retesselate as the view changes, or does it just tesselate once and push facets?