This is a different issue from
20201120-8f78be34c4-win_x86 CPU usage unusually high in Windows.
When I minimize the clients using the minimize button on the upper right hand corner of the window, it sill use the extra CPU as indicated in the other feedback, however, after it finishes it will go back to zero CPU usage.
Now, if I minimized the windows using 'show desktop', it will NOT return to 0 CPU after the script finishes. The remaining CPU usage disappears when you re-show the window and then minimize it again using the button in the upper right hand corner.
To me this sounds like a different kind of message handling in the Windows message queue when minimizing, where one thread in the program is aware it is minimized and the other thread is not.