Equitable Sharing between TCP Sockets

[list-freebsd-2004 at morbius.sent.com (R. W.)]

I'm using 5.21 on a desktop computer with a dial-up modem. I tend to 
have several applications simultaneously sharing the connection, and 
I'm finding that this aspect isn't working as well as it does under 
windows 98. 

Under windows each tcp socket would tend to receive at about the same 
rate, and intermittent, interactive applications would quickly gain 
their fair share. Under FreeBSD a couple of sockets at a time tend to 
hog most of the bandwidth, and interactive applications get frozen out. 
I don't know what Windows is doing right, but I'm guessing it has some 
kind collective management of tcp window sizes, probably tied-in with 
the slow-start algorithm.

Is there any relevant setting I can alter in FreeBSD 5.x  to improve 
it's behaviour?