The configure script that comes with irrd looks for pthread_create in libc_r, which does not exist on freebsd. The result is a single threaded irrd, whose performance is awful. Simply autoreconf'g appears to be sufficient, though it generates numerous autoconf errors.
A commit references this bug: Author: ume Date: Fri Oct 16 11:13:51 UTC 2015 New revision: 399431 URL: https://svnweb.freebsd.org/changeset/ports/399431 Log: - Fix pthread detection. [1] - Add LICENSE. - Use USES=tar:tgz. - OPTIONS'fy. - Don't hide install procedure. PR: 203792 [1] Changes: head/net/irrd/Makefile head/net/irrd/files/patch-configure
Thank you for the report. It should be fixed now.