If they had released a demo, nobody would have bought it in the state it was released. Well, OK maybe the extreme supporters would have... Just stating the brutal truth.
I heard things were much better after fall patch so I took a chance and picked it up on sale. I wasn't expecting a lot from my 6 year old quad workstation (specs below), but it handles it OK and I can enjoy the less demanding missions at mostly mid settings with a few on high, some turned off. It is stunning when running well, and I understand why people whole-heartedly defend this sim.
Perhaps stating the obvious here, but better multi-threading makes this possible. To compare, RoF runs very well on my aging system, but their optimization is much better than CoD at the moment. With time and resources, and a forthright approach with customers, CoD can recover from the shaky start and hopefully win over the crowd it deserves.