I have 2 nearly identical 15" macbookpro laptops. One was purchased on Jun 24, 2011 ( Order # , snow leopard), and the second on Nov 03, 2011 (Order # Lion), . Both machines have the intel 2.2 GHz quad-core i7 processor. Every effort was made to make these two machines identical. But the first machine runs about 3 times faster than the second. I do very computationaly intensive runs that solve mathematical equations through thousands of iterations that may last 3 or 4 days. The slower machine would take 9 to 12 days. When I set up my first macbookpro, one question asked was "When I do intense computations, do I want to distribute the workload among the cores?" I answered YES. But the setup for my second (slower) machine never asked that question. The difference in speeds is too dramatic to attribute it to snow leopard vs Lion. What do I need to do to make my second machine run as fast as my first to take full advantage of the processor?