Hello,
I recently (okay, it was yesterday) installed OpenBSD 6.3 i386 into a virtual machine using the usual qemu/kvm constellation.
My intent - in case it matters - was to test a bit of software I am working on across several platforms; OpenBSD tries to be a very harsh environment for misbehaving applications, which makes it an excellent system to do such testing on.
But the performance is … problematic.It is ridiculously slow, when I ssh into the VM and type a command, there is a noticable delay between me hitting the key and the corresponding letter appearing on the command line. As if I was connected through a slow modem or something.
I have another VM running on the same physical host, this one is running Void Linux, and its performance is very snappy.
So I wonder if OpenBSD is known to have performance issues when running under KVM?
The issue is not network-related, I think: When I open the console and login there, the problem remains.
I also have a small home server running FreeBSD, where I have an OpenBSD (amd64) VM running on bhyve, FreeBSD’s native hypervisor. It is slow, too, but not nearly as slow as the one running under KVM, even though the FreeBSD host has a far slower CPU.
Is there a trick to getting this to work nicely, or is OpenBSD just a hog in virtualized environments? I know performance is not their main goal, but my experience running OpenBSD on real hardware has been okay.
Also, is this the right place to ask? The longer I think about it, the less I am certain if this is a KVM problem or an OpenBSD problem. I am asking here first, because the OpenBSD crowd tends to deal harshly with people who ask stupid questions like me. 
Thank you very much for any insights you might be able to share with me,
Benjamin