FreeBSD 9.0 did an unannounced appearance lately. it introduces a bunch of different features, two of which are of great interest to me.
firstly, we can select different mechanisms to fight traffic congestion for TCP. to do that, you need to change sysctl net.inet.tcp.cc.algorithm from the list available under net.inet.tcp.cc.available. NewRENO, the default one, works quite OK, but in some specific configurations you can select others and check if they’d behave better.
secondly this change introduces support of NetFlow v9 standard by ng_netflow module for Netgraph. i haven’t had time however to check if it works, so this has to wait a bit.
of course you can see the whole list here.