Opening the start-menu, krunner (through Alt-F2) or the like results in 10-20sec delay before the expected window opens.
it's suggests that it might a problem related to the RedHat-patch xserver-1.7.1-window-pictures.patch (removing it seems to resolve from the problem for some folks).
*** This bug has been marked as a duplicate of bug 533620 ***
As mentioned in that bug I gave the quickfix from Rex Dieter a try. Installing his xorg-packages (with the removed redhat-patch) worked:
For further information please see above mentioned bug.