Stack Machines, Koopman is the only treatise that I have seen that really digs into the question.

http://users.ece.cmu.edu/~koopman/stack_computers/index.html

My memory of the conclusion is that register machines are a bit faster for general programs. Stack machines are better in some special niches. (High volume/rapid Interrupt handling comes to mind)

I should read the book again myself...