Computer is an atom 320 with 512MB RAM. Ubuntu 8.10. While not a powerhorse, I'm not sure this is quite normal. Setup is an idle xubuntu desktop with the CPU, Network and Memory taskbar applets. These applets display usage by means of vertical progress bars. If in the xfce theme selector I choose either Human or HumanClearlooks themes, Xorg CPU goes, according to top, to 30-50%. I note that these themes animate progress bars continually (slanted darker bars that move), but I don't know if this is actually related. Chosing other theme (for example the default one), CPU drops to 1-2%. Having compositor enabled or not does not make a noticeable difference (perhaps a 1%).
How is that a bug in Xfce? We do not ship the Human theme, we do not default to that theme. I fail to see the sense of that bug report.
You are correct. I'm sorry about this one. Please close as invalid.