This is a good suggestion. OP could also mount /usr/ports, /usr/obj, etc. via NFS from a dedicated build machine, and just pkg_add the built packages from /usr/

This is a good suggestion. OP could also mount /usr/ports, /usr/obj, etc. via NFS from a dedicated build machine, and just pkg_add the built packages from /usr/ports/packages/, or 'make install' precompiled errata from /usr/src/. Having a dedicated build machine also keeps all the build dependency stuff contained elsewhere, and makes it easy to update multiple machines.