LibraryMan wrote:

> OK, as an example, here's what I get after commenting out area lights, sky
> sphere, and a not-very-complex wall object.  Is it typical to have the
> bounding box(es) take such a high percentage? (I really don't understand
> what I'm seeing here)

OK, let me see what we have here...
 

> Bicubic Patch                  1897457               0      0.00

Hmm... There's a bicubic patch somewhere in the scene, but it is not 
visible at all: no intersection tests succeeded. It might be behind the 
camera or something.


> Box                          398678261         1683150      0.42
> Cone/Cylinder                 30031777         2434654      8.11
> CSG Intersection             215095850         1551946      0.72
> CSG Merge                      1113026           18718      1.68
> CSG Union                    197475969          266424      0.13
> Torus                        589217202          120998      0.02
> Torus Bound                  589217202          151459      0.03

As you see, very few of the intersection tests with these types of objects 
succeeded. For some reason, POV is doing a _lot_ of unnecessary work, 
checking rays against complex objects, but failing to find intersection 
points.


> Bounding Box                 271143478       269643947     99.45

This is also rather strange. You seem to have a very loose bounding, with 
the actual objects taking up a very small part of the total volume of 
bounding boxes. That's why almost every ray hits a bounding box, but when 
POV then checks a ray against the objects inside the box, it fails.


Conclusion:
Most probably you have a complex CSG construct of which only a very small 
part is actually visible. POV cannot calculate an effective bounding 
solution to such an object, so it ends up making a lot of work in vain. If 
you bounded your object manually with bounded_by { } and tried to get it as 
tight as possible, the render speed would probably increase a lot.

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