FYI I installed fedora 7 test2 in parallel with feisty. It has the same versions of metacity and xserver but it doesn't show this problem. But libX11 is still at version 1.0.3 in fedora while feisty has 1.1.1. Perhaps xcb is the problem? -- Sluggish rendering since xorg 7.2 update https://launchpad.net/bugs/88815