OpenBSD kept making snide remarks at FreeBSD for not keeping the pf codebase in sync. FreeBSD also didn't import the newest version the last time they synced because a slightly older version was faster.

Then FreeBSD hard forked pf and made it multithreaded.

Now FreeBSD's pf is the fastest implementation of pf but is missing the latest features/syntax and may have some bugs that were already fixed.

Meanwhile IPFW is still faster than pf anyway, so I don't know why people even care.