Creating global Geoprocessor object for ArcObjects application?

I develop and maintain a tool built in VB .net which makes use of the IGeoProcessor. When my code calls a function that uses it, it creates and destroys within the function. I've seen no particular drop in performance. There may be a small cost in instantiating it but that seems to be trivial when compared to what tools it executes.

As long as its not being created and destroyed say in an inner loop within a function then I think you are OK in creating it and destroying it within a function, well that's what I do.