sysctl.conf for your high traffic server - under high load :

security.bsd.see_other_uids=0
net.inet.tcp.recvspace=65535
net.inet.tcp.sendspace=65535
#kern.ps_showallprocs=0
kern.ipc.shmmax=67108864
kern.ipc.shmall=32768
net.inet.tcp.inflight.enable=1
net.inet.tcp.blackhole=2
net.inet.udp.blackhole=1
net.inet.ip.rtexpire=2
net.inet.ip.rtminexpire=2
kern.ipc.somaxconn=1024
net.inet.ip.check_interface=1

kern.maxfiles=32768
kern.maxfilesperproc=2000

kern.ipc.maxsockets=163840
kern.ipc.maxsockbuf=2097152

net.inet.ip.fw.dyn_syn_lifetime=1
net.inet.ip.fw.dyn_max=65535
net.inet.ip.fw.dyn_buckets=256
net.inet.ip.fw.dyn_udp_lifetime=5

net.inet.tcp.msl=7500