Like watching paint dry

Here are some ambient occlusion renders of the kitchen scene. The trouble here is that the shortest of these renders took nearly five hours, and the longest one took over six.
The original size is 1920x1080. I rendered with Mental Ray using its Ambient Occlusion shader with 128 samples, but I think the real killer is the motion blur. MR is painfully slow in rendering it, so I will be trying to do the motion blur in the compositing stage.

It may seem like not a ton has changed since the last ones I posted, so why the ridiculous render times? I've been tweaking virtually every model in the environment. I've been smoothing polygons so their profiles are not jagged (this is probably where much of the render time is coming from), deleting poly's where they are not seen directly by any camera or in any reflections, re-laying out UV's and setting Normal angles. I've also converted some poly objects to subD's or altogether replaced them with NURBS because I know that I'll be using procedural 3D projections for their shaders and therefore won't have to worry about UV maps. I'm still going to try to optimize my scene for rendering.