In case it helps others ....
I did an online chat with an Intel rep and described the situation as above. He asked if I had RAID drives on the laptop. I do not. He said to uninstall Rapid Storage Technology. I did that and everything reboots clean and my CPU usage is back to normal. I presume that fixed it unless something else arises over time, with use. If so I will update this thread.
Thank you for contacting the Intel Communities.
I am glad to hear that you were able to release the CPU usage in your system with Windows 10*