A shutdown takes several minutes. It is caused by /etc/init.d/networking/red.down/05-update-dns-forwarders. This script is called from /etc/rc.d/init.d/networking/red after the network was deconfigured - so unbound cannot update forwarders and runs into timeouts.
I have increased to major usability issue. Instead of much less than a minute a reboot needs more than 4 minutes in my case.
Ah, it will be fixed with core111. Check: http://cgit.ipfire.org/ipfire-2.x.git/commit/src/initscripts/networking/red?h=core111&id=ebf64a93ee01f18226a8ed465a188f976097ee34