right.
Here is another tool available from Windows Task Manager:
Resource Monitor
it shows CPU, Disk, Network and Memory utilization.
Even when network is quiet, Windows Update uses CPU and Disk
In services tab of Windows Task Manager find the Windows Update service 'wuauserv',
right click, Go to Process (click on Show processes from all users in Processes tab beforehand). This would give you pid with which you can check CPU, Disk etc in Resource Monitor.