Aye, if the render times are killin ya, do't bother with Bryce's silly DOF options. They are horrendous. Just use a distance mask, and Photoshop or Paintshop, and you can run the blurs much more accurately and quickly. If you're interested, there's a thread we went over this technique in, awhile back. The main problem with Bryce's DOF is that it's too render-intensive. It is entirely un-animatable.