If you have shadows on and reasonably large textures, 4-6 minutes for a render in Production mode is not excessive at all. They do take time. There are many ways of limiting the render time. I remove bump maps from figures that are not close up. If you can't see the bumps anyway, you can save render time there. For figures and props that are not close up, you can also try to reduce the texture resolution. You don't need a 2000x2000 face texture if the face is just 20 pixels wide in the finished picture... You can reduce the texture size in a picture editing software. For an animation, the total render time is pretty much the sum of all individual pictures. No way to get around that. This is the reason that Hollywood animation studios were the biggest customer for Cray supercomputers when those were the computers of choice...