Use mental ray, the motion blur is alot better and you just need to set up the bsp settings if your using motoin blur (lower bsp size maybe). that will help, use the diagnosis tool under mental ray globals to tweak the bsp.

Tweak the antialias contrast tollerences and filters so you get nice edges in a short amount of time, and only use production quality sample levels when your at final render.

In terms of ray tracing make sure you dont have the trace depth too high than you need, that can realllly slow things down.

Things like Depth of field can slow down render time alot.

hope that helps