how many polygons is too many polygons?

when importing a piece of geometry into touch, are there some guidelines as to how many polygons is appropriate so as to not hog all the cook time?
(by the same token are there any specific guidelines regarding rendering times for different types of geometry, you know so that we can know that importing geometry made with polygons, for example, will tend to render faster than say geometry made in nurbs)

There is no answer to the first question really (answer to 2nd question later on). There is no # of polygons where Touch will suddenly get really slow. It’s totally dependent on what SOPs you are using, your CPU speed, your memory speed, your video card speed, the MATs that are being used etc.

But there are a few factors to consider that can help you decide.
For CPU speed:
The amount of time a SOP takes to cook can increase based on the number of polygons, or just on the number of points (I assume in your case they would both increase together). The cook time will increase pretty evenly as you add more polygons/points, so the answer to ‘how many is too many’ is totally dependent on what SOP operations you are doing, and how much extra CPU time you have in your synth (if its not doing much else, you can have more complex geometry). Try with a small amount of polygons and a large amount of polygons and find a happy medium that gives you the speed/quality you need.

For GPU speed:
Generally the number of polygons doesn’t matter anymore on todays graphics cards. The number of pixels drawn is far more important that the number of polygons. 1 polygon that covers 100 pixels will render at about the same speed as 100 polygons that cover 1 pixel each (maybe the 100 polygons will be a little slower, but not much). You will get much bigger gains by using lighter shades, less lights, reducing overdraw than reducing the number of polygons, if your video card is what’s holding back the speed of the synth. There are some articles on the wiki about optimization.
But sorry there is no number I can give you, try and see is the only way. Its too dependent on too many factors for us to be able to say.

For the 2nd question:
Quads, Triangles and long triangle strips are the fastest geometry to render. NURBs and Beziers are very slow since GPUs don’t actually support them. NURBs and Bezier’s need to be converted by us to lines/polygons on the CPU before rendering, and this is a very slow operation.