in my test shadows were not flickering and camera was very smooth.

it's true that when you add physics, AI and other stuff it will go even slower but i believe that those models and island are very high poly models. and that in games you wont use so many polygons, at least i wont.

it looks like a good engine to me but i'd like to see it in some interactive example like some small game.

btw, try testing with AA off