I have turned off shadows in the video options. It also increased frame rate quite a bit.
Being a game dev myself I can tell you that adding prerendered shadows to a game like this after release is probably not going to happen.
Id be partially happy if they could just add blob shadows to the characters.... even if static shadows for other things never happened.
Im playing with no shadows too right now, not for performance reasons. Blob shadows would greatly improve my visual experience with the game.
