Just upgraded a 3rd Gen Lenovo Carbon X1 from 15.04 to 15.10 and I noticed a rise in CPU usage.
/usr/sbin/NetworkManager is using ~35% constantly and /lib/systemd/systemd-journald seems to rise when NetworkManager is started (drops when it is stopped).
Turning of the wireless adapter does nothing. Turning off bluetooth also does nothing. No LAN is connected.
Stopping the service fixes the problem, obviously, but this is not a viable option.