FreeBSD 7.2 as gateway has problem with Orbitdownloader

Lynx

I have a freeBSD 7.2 system as a gateway/router server, using NAT to provide internet. Problem appears when one computer in Networks has a runing Orbitdownloader; if Orbitdownloader is downloading with speed ~300KB/s, the other computers in Networks can "ping" the server, but can't connect to internet; if downloading with speed ~500KB/s, the others can't ping the server and can't connect to internet.
CPU ~93% Idle, ~4% natd
We have 40Mbps bandwith connecting to internet
What is the problem?

Sharp

The problem is that you are using natd — it's very slow.
Use ipnat (man 5 ipnat, man 8 ipnat) or pf nat (man pfctl, man pf.conf)

sergey_m

Не настолько он медленный. Проблема в чём-то другом.