Changing to HWv10 improves frame rate to a mostly consistent 21-30 fps. Compared to HWv11 or 12, 10 at least improves playability tremendously. Still dropping below 10 fps in indoor areas with a lot of sporadic lighting and heavy with shadows, as well as outdoor areas with a lot of activity such as in cities with a lot of people.
I have tested Hardware Version 10 with 2 and 4 vCPU's and 4 certainly performs better than 2 on both the iMac and Macbook Pro.
I am running with Unity turned OFF and at full screen on both machines.
I'll mark RichShu's answer as correct in a couple of days if there are no more suggestions over the weekend.
Hopefully Fusion improves in this area but perhaps this game is too old to benefit from future improvements. I also tested Skyrim with Parallel's 9 and it performed as well as Parallel's 10. Both run the game from 15 to 25 fps faster, with higher graphics settings and no hiccups indoors or out.
Thanks again everybody.