opaque window moving very slow in 1.6.1

[Mark Diekhans <markd kermodei com>]

After building sawfish 1.6.1, the window movement (opaque
animation mode) has become sluggish to the point of being 
unusable. On a 1920x1200 display, moving firefox causes
the X server to hammer the CPU to 70-90% busy.

This is on a CentoS 5.2 system without root access, so it
required building all of the gtk+ dependencies and sawfish
into a separate directory.

Previously, I was running a version from the old svn tree
from around 2009-04-14 and it was very fast.

Moving aside my configuration to see if I have something
in there results in the error:
   Error: Can't start gtkrc-style-program