Algorithm

Problem solved; thanks for the reply though.
With Event Viewer open, I ran the program to set the reduced on-level, and was surprised to see ISY attempting to write to several different devices, with the bathroom SwitchLinc being last of all, and taking about a minute-and-a-half, which explains the delay.
On examining the devices, I discovered that they were all wireless devices which had updates pending, and a closer look showed, in the Administrative Console, that the button to automatically write changes to wireless devices was enabled.  I normally keep that button disabled, and it seems that when ISY reboots, it enables that button--something to be aware of in the future.
With that button now disabled, and again running the program, response was immediate, and all is back to normal.