Comment 19 for bug 104013

I was having the same problem but only on one of my machines so I decided to do some diggin'.

Here is what I found.

The hosts that exhibited the high cpu usage when moving windows around, minimizing and maximizing windows and most of all running system monitor (graph view) did not have xserver-sgl package installed.

Once the package was installed BAM, system monitor runs about 5-6% cpu in graph view. The most import part is that when moving windows and min/maxing them, there is no more lag!!!!!

So do the needful, sudo apt-get install xserver-sgl. Once installed, ctrl-alt-backspace to restart X.