I've got the same problem on a nVidia Corporation GF104 [GeForce GTX 460] (rev a1). After cloning the screen the system gets unusable; Compiz gets a relatively high load (~0.9 on a 6-core). Load gets lower after a while, system becomes usable again. Some Compiz plugins (desktop-zoom for example) do not work after this.
I've got the same problem on a nVidia Corporation GF104 [GeForce GTX 460] (rev a1). After cloning the screen the system gets unusable; Compiz gets a relatively high load (~0.9 on a 6-core). Load gets lower after a while, system becomes usable again. Some Compiz plugins (desktop-zoom for example) do not work after this.