Ubuntu

Comment 44 for bug 193578

High CPU usage for Xorg is ironically not an X problem. X is a server so simply responds to client commands. If a client program has a bad algorithm that calls too many X calls too rapidly, all those X calls will show up as charged to the Xorg process, when really the bug is with the client app's algorithm.

See http://wiki.ubuntu.com/X/Troubleshooting/HighCPU for more info.