tproxy and NATed packages

["Behnam B.Marandi" <blixbox@xxxxxxxxx>]

I'm testing a squid/tproxy enable cache machine in a network with some 
clients. one of them does NAT it's users via a PIX machine. Every time 
we put them behind tproxy/squid, web transfer slows down which is almost 
unusable and most queries got time out response.

Does anybody know why this happen? If a packet NAT once - or twice - 
before cache machine, then tproxy might not be able to route it correctly?

Behnam.