I am skeptical that it will get any slower if you use slower disks. I think a lot has to do with the client too. It is pathetically slow and old software that client is written in.
I wont be surprised if your chart open/close will get worse if you used 8GB and 2 cores.
Srini IT Support/Bookkeeper/Manager (for my wife's nephrology practice) (My Real job is Engineering Manager software company)