I’ve gone through everything again and just can’t find anything “wrong” with the Project itself causing the hanging. I really think it is rendering/graphics/viewport at the root of the problem. Hiding the viewport with another tab/window makes all the stutter go away from all other open windows. The viewport rendering is causing the stutter, everything is pointing to that, I’ve had Maya and Motionbuilder run awful with a new rev. that hated current video drivers similarly.
As I mentioned - 980GTX with last three current drivers has identical problem/symptom. I know Epic played some games with up-sampling and AA for 4.19, I’m wondering if they changed some default Project rendering setting or such viewport code that is causing a problem on my specific card. I can’t be the only one.
If Epic (or anyone) can please suggest or think of what was tweaked and/or new default//render 4.19 settings that could be affecting my viewport so adversely, I’d really appreciate the input.