I'm going to move the guest to a physical box anyway, but has anyone using HyperV come across this sort of issue recently....
Have a VM running Windows 10 which is hosting HmailServer, a basic webserver and SpamAssassin. Was all running perfectly fine until update 1903 installed. Since then, the VM was running like a dog, taking 5 minutes to log in. Initially it was bearable as I didn't need to log into the system that often and it didn't seem to affect anything as such.
However now, I have to force a reboot of the system to be able to log in - when I'm logged in, Vmmem.exe on the host sits around 12% CPU usage. The second I disconnect/logoff the VM, Vmemm.exe shoots upto anything from 25%-57% and the whole system almost dies - even the webmail system absolutely crawls and times out when talking to the mailbox.
The other two VM's on that host are running fine, but are Linux and Windows 7 based.
Frustrating as hell :)