Comment 22 for bug 426556

To troubleshoot high CPU usage caused by the dbus-daemon process, you can use the
"$ dbus-monitor --session"
command to monitor the messages being sent through dbus. If you notice a particular application sending a large number of messages to dbus-daemon, it may be the culprit. In my case, I discovered that my break taker app was sending lots of messages to dbus-daemon. After stopping it, the dbus-daemon CPU usage returned to normal. To identify if there is another app causing this issue, you can use the same command and observe if any message is frequently being sent or not.