There's only one thread in gnome-panel. I have identified gnome-panel as the exact program, but it's the window list applet that causes the slowdown [disabling it causes the problem to go away]. I attached a gdb session to it and made several backtraces while the gnome-panel got slow. A new note: the cpu usage goes up only when switching workspaces/iconyfing some window/otherwise changing the appearance of the window-list. On other times the whole panel works ok. Applets working in separate instances (i.e. Tomboy) are not affected at all, but applets working "inside" gnome-panel process, like the gnome-menu, (I don't know the exact architecture, just noticed that some applets have their own processes, so sorry for inprecise wording) are all blocked of course.
I have attached the backtraces with some annotation. -- Gnome window list causes gnome-panel to eat all CPU https://launchpad.net/bugs/56289 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs