I have 6 Debian Squid boxes with two nics.
I didn't have any problem with them but today I realized that Debian boxes are using ipv6 connections on eth0 cards.
(I realized this when I was updating)
and because of this Google (http) requests are too slow.
I check google request in front of the squid machines with ipv4 on a windows7 machine and everything is fine. Fast as usual.
I had this issue on and after IPV6 Day, but back then I have no time to inspect this and later found out that problem was gone. But now it started again.

What should I do to solve this ?
Thanks in advance.

try:

tcp_outgoing_address 127.0.0.1
or
tcp_outgoing_address [external-interface-ipv4]


good luck.

1 members found this post helpful.

I solved my problem by disabling the ipv6 in kernel.

echo net.ipv6.conf.all.disable_ipv6=1 > /etc/sysctl.d/disableipv6.conf

After that you have to reboot.

Thanks