Very good question!
I got frustrated with the performance with the stock PC from the very beginning. Only after bothering my vendor for months (!!!),I got help and some one form 3shape got onto the PC and tweaked something, which helped to improve it a bit. I upgraded to one of the higher end gaming PCs 2 years ago, or so. Although it exceeds all the minimum specs by miles, it still stutters on certain tasks and the periodical saving process takes forever. Before upgrading, I contacted my license holder on what to buy, but their advice was useless. My friend next door has Exocad (ZirkonZahn) and he runs it on a similar built PC, with no issues. Very smooth, even a few years ago, when he had a less powerful computer.
For 3Shape, from what I gather, look for the best performing single core processor. Obviously a good graphics card and decent ram.
However, what I don't get, it seems, when using Dental Designer, the PC barely gets challenged. No fan spinning no nothing and task manager shows usage in the 10 to 20 % range. I really ask myself why we buy these high end computer when the software is not using it?
I am looking forward to be educated on that!
Thanks!