Can someone please explain to me how important Processor Speed is? Because currently you can get a 13 inch rMBP with a processor up to 3.0ghz with a turbo boost up to 3.7 But the 15 inch rMBP only lets you get a processor up to 2.8ghz with a turbo boost up to a 3.8. Now obviously to a layman like myself I would think more is better. So how come the 13 inch can offer more than the much more power 15 inch? Or does it not really matter? I mean it must right....? That's why Apple charges you to upgrade to a faster processor speed? Can someone help?