Mavericks Server: DNS: Increase forwarder timeout
A DNS server that is configured to use a forwarder behaves as follows:  


When the DNS server receives a query, it attempts to resolve this query by using the zones that it hosts and by using its cache.  
If the query cannot be resolved using local data, the DNS server forwards the query to the DNS server that is designated as a forwarder.  
If forwarders are unavailable, the DNS server attempts to use its root hints to resolve the query


I doubt such timeout setting exists. Any timeout setting would just slow down the query forwarding to the forwarders. Additionally both forwarders (Fritz!Box/OtherDNS) you define in the Mac Server settings would suffer from a timeout.

Skip the Fritz!Box and add one or two reliable &amp; fast DNS servers (OpenDNS/Google).

You may check namebench to get some other fast and reliable forwarders.

I use the same setup (Server/Fritz!Box) and i get 50 ms from localhost and 77 ms from dnscache.berlin.ccc.de.