When a single robot does a tiny bit of each task, it is multiplexing. This is known as a context switch. They take time, because the robot must switch from one task to another and return to the point where it had left the task. The same happens with the cores and the threads.
Now, we are going to use Process Explorer to analyze context switches in a core:
procexp.exefile. A window with a complete running processes tree list with its icons will appear.