I was fooling around this weekend and saw an alert from Windows Security that Memory Integrity was turned off and should be turned on. I turned that on and the guest became incredibly slow taking minutes to load everything after a boot.  I disabled Memory Integrity and the guest performed normally again.  This feature is under Device Security.  (It turned out one of my upgrade VMs had not turned it on due to a VPN driver so I am rid of that now at least.)