>I think I started this tread, but it has evolved somewhat from my original question. I confess that I am surprised that I get the feeling from reading this that you guys (who are the experts) really don't understand the memory model that VFP uses to do classes. I agree that we have never really questioned this before because it worked, but I want to understand it now because I do think that it can have a big impact on performance when classes are used in a major way. Is it possible that Microsoft would release this information for us.

I kind of doubt it. Microsoft holds all their "proprietary" info quite near and dear to their heart.