I understood your code and tried on both single processor and dual processor. In single processor, the difference in processing time is pretty much similar. But in dual processor, I can see some its significant faster but no way near to your QUAD machine. Anyway this was very helpful learning experience.
One question: What the "Reentrant" option in execution properties does exactly? I was trying to find some explanation about these.
Reentrant makes mulitple copies of a function so that each can run independently. Non-reentrant vis can only execute repeatedly sequentially. If you use a non-reentrant vi in a program in two locations, one would have to wait until the vi is done executing in one part of your code before it can execute the second time. If you make the vi reentrant, then two copies of the same code is executed possibly at the same time.