Since R14, Autocad was never lagging on any machine in the past but it opens up much faster with SSD. We use Autocad MEP 2013 so it has a lot of stuff to load each time and on computer with HDD it was really taking some time. Revit also loads much faster. Starting a program is the most noticeable and comparable, more than actual work. But since Revit works on local drive even if you store projects on the network, than it has to be faster on SSD. In reality, besides starting programs, I never noticed significant speed improvements but it is typical case when upgrading. I'm sure that when I sit down at another station with HDD, I will be surprised how slow it is. Anyway, I don't see any lagging in Revit now, it's unbelievable how fast you get used to good stuff. The improvement is not a Wow! but I don't see a reason to save a few bucks (stretch that extra cost over 2-3 years of using this machine) to get more useless storage if you have network. In todays CAD, and it always been, speed is what we need. I'm very happy, not excited but happy that my new computer has SSD.