I have the same problem. And also selection rectangle on the desktop works extremly slow. It begins to work OK after restarting the compiz. I tried both of compiz versions: from the oss repo and from the X11:XGL one. Result is the same. Feature from the how-to mentioned abowe seems to shorten hanging time a bit.
LG R500 laptop. Nvidia Geforce 8600M GS, openSUSE 11.0 i386, GNOME.