[csdreamer7]

Good point. Microsoft probably spends a lot more than 600K on Linux kernel developers alone to implement several of their features including Hyper-V.

One of the reasons I know it is slower is due to security.

With the security mitigations OpenBSD chose to simply disable SMT. It is a less performant, but much simpler solution than the software mitigations that Linux and Windows implement.

https://www.phoronix.com/scan.php?page=news_item&px=OpenBSD-...

Do you know of any other reasons?

[rfoo]

OpenBSD developers do not need high performance, so naturally OpenBSD and its components are usually just not optimized for performance.

One famous case: About 15 years ago, someone made a patchset called HPN-SSH [1] for OpenSSH because:

> SSH implements a multiplexed connection protocol so a single TCP/IP connection can host multiple SSH sessions at the same time. This means that SSH also has to implement a flow control mechanism in order to make sure that the network connection isn't overwhelmed. Much like TCP/IP, it uses a receive buffer to indicate how much data the sender should be sending at any one point. The developers of OpenSSH had initially set this buffer size to 64KiloBytes.

This capped scp/sftp bandwidth on a 10ms link to about 50Mbps. At that time no OpenBSD developers would like to work on this because... they don't have >10Mbps NICs (or link? I don't remember) so they never feel the problem.

Of course the thing eventually got fixed, but much later.

[1] https://www.psc.edu/hpn-ssh-home/hpn-ssh-faq/

[gjadi]

It makes sense, doesn't it?

Do not accept code that you know you won't be able to maintain or test.

[rfoo]

Yeah, it totally makes sense. It just shows that people are not paranoid enough to give up their usual performant OS and invest in OpenBSD :)