This tracker is open in a sense that everyone announcing a torrent is welcome
to do so and will be informed about anyone else announcing the same torrent.
Unless -DWANT_IP_FROM_QUERY_STRING is enabled (which is meant for debugging
purposes only), only source IPs are accepted. The tracker implements a minimal
set of essential features only but was able respond to far more than 10000
requests per second on a Sun Fire 2200 M2 (thats where we found no more clients
able to fire more of our testsuite.sh script).

Some tweaks you may want to try under FreeBSD:

sysctl kern.ipc.somaxconn=1024
sysctl kern.ipc.nmbclusters=32768
sysctl net.inet.tcp.msl=10000
sysctl kern.maxfiles=10240