Mark, great stuff and wow zemax really smokes with 8 cpu's. Will this help with non-sequential tracing as well - say scattering or is it more complicated than the number of ray surfaces per second in the NSC mode? {Reply: yes, it works just great with non-sequential ray-tracing too. Its harder to define a single figure of merit, like RSS, but performance scales pretty much directly with number of CPUs in NS mode too, including scattering, splitting etc...everything!}