I believe none...

By "shadows" on i mean are you're lights casting shadows?
-Have you checked the render log?
-Have you tried Render -> Render Diagnostics...?
-Have you tried File -> Optimize Scene Size?
-In the...

2 days = 48 hours = 2880 mins
2880mins / 600 frames = 4.8 mins per frame = 4mins 48 secs per frame. sounds awful lot to me considering what you have in the scene...

how many lights do you have...

try it with default materials. it might be the tessellation part which is taking the time. and btw, do you have shadows on?

to me this seems to be taking too much time to render with your hardware. check the render log and see what is the most time consuming part when rendering a frame.