I think the answer is too many theme objects at the "Normal" Z-order level. If I move a bunch of graphics and text and shortcuts to the "Desktop" level then the speed of the tray, PS and ODPlus return to normal. But with this theme, you have to be careful, because if you move key elements to the desktop level then applications will not respect the bar's position when they are maximized.
Cheers,
Jeff
PS - I don't know exactly which items are "key" and which are not, but it involves several hidden (not visible) objects. I kept moving objects to the desktop level until I got normal performance and maximized respect, and then I stopped.