I built xfce4.8.0 and xfce4-desktop 4.8.1 with --disable-thunarx. I changed the icons to be shown on the desktop to 'Minimized application icons'. In the previous version (4.6.2), such a setting with just give you an application menu instead. But, if this feature is enabled in this version, the CPU will grow to 100% soon. 

I checked the source code, it may be caused by idle_add, or the new garcon. I don't know. 

~> uname -a
FreeBSD compaq.yuetime 8.2-STABLE FreeBSD 8.2-STABLE #0: Thu Feb 24 18:11:55 CST 2011     root@compaq.yuetime:/usr/obj/usr/src/sys/HOUKAGO  amd64
~> pkg-config --modversion glib-2.0
2.26.1
~> pkg-config --modversion gtk+-2.0
2.22.1
~> pkg-config --modversion exo-1
0.6.0
~> pkg-config --modversion garcon-1
0.1.5