There are known clock/timer issues with OpenBSD under KVM due to what appear to be bugs in KVM.
There is some info in the following thread: https://marc.info/?l=openbsd-bugs&m=151430928212450&w=2 I'm afraid you are on a wild goose chase. The behavior you are seeing is not what you'd see on bare metal or on a different virtualizatoin platform. - todd
