Your VAR is incorrect in this case. The hard drive access will only become a factor when saving, or when working with large models. Typically when running IronCAD, everything you are workin on should be in RAM. If you either have a small ammount of RAM or an extremely large file, then you start working from the pagefile, which is just hard drive space allocated as fake memory (overflow really).
I would also say, that in this case, that not only the processor and memory differences are contributing to the slow-down, but also the video cards. IronCAD still needs to draw your parts when their locations are calculated, which falls mostly on the Video card. I noticed that you are running both "MX" versions of the Geforce "gamer" cards. The MX versions are stripped-down affordable cards with less horse-power than regular Geforce cards. My bet is that if you put a CAD card in your slower computer, you might be able to come close to the performance of the faster computer without changing anything else (close being a relative term... heheh).
So... basically it is just a hardware difference. You want to test the hard drives, do a "save time" test (and in actuallity this will still be dependent on memory and processor speeds).
Hope that helps. I will say, that I went from a ATI 9700 to a NVIDIA Quadro4 and there was a HUGE performance increase... same machine.
Hope that helps. Tell your boss to spend the big bucks on processor, memory, and MOST importantly, video card. I love watching big models rotate in real-time. It is like geek-porn!
Mike T