OpenBSD's performance is atrocious. Scrolling the browser laggy and unresponsive on my ThinkPad x220, and closing tabs sometimes results in multiple-second freezes.
That's maybe good for a router but simply not HPC material.
Nobody wants to use OpenBSD HPC. Everybody wants to use Dragonfly BSD HPC, if not many drivers were missing. Dragonfly MPI outperforms Linux, Linux just has more HW support and a bit better TCP/IP stack.