The flicker may just be motion blur, depending on your visual goals you can just disable it on the Post Processing volume or do something more fancy like turn it off, move the camera, then turn it back on.
I’d really like to test what Ze0rb suggested in Blueprint, it’d be a good measure of how terrible clearing and re-creating multiple Instanced Static Mesh components really is. I think I’ll try to throw something together this weekend that does that.
And I am loving this thread! So much good stuff here.