Comment 17 for bug 433972

I see the status of this bug has been changed to "fix committed", so I don't know if my two cents will still be of assistance, but I have had the same problem.

I previously used Ubuntu 9.04 and had no problem.

I did a clean install of Ubuntu 9.10 and the internet is slow.

I am able to download at regular full speed, but there is a lengthy delay in everything. When entering a url into Firefox 3.5, it takes a long time for any website to begin downloading, but once it starts, it's downloads regularly. Connecting to instant messaging protocols, through Empathy and Pidgin, also takes much longer than normal.

I followed this tutorial to change my "rwin" value, which originally appeared to be very high.
http://www.uluga.ubuntuforums.org/showthread.php?p=7098253

I had the problem before I changed those values, and the problem remained after I changed those values.

The default setting in the latest versions of Ubuntu is "Automatic", to receive a LAN IP address and DNS addresses from my modem-router. Using this default setting, Ubuntu's Connection Information always showed the Primary DNS address on my Ubuntu PC to be the LAN address of my modem-router. I just now set my LAN IP address and DNS address manually in Network Manager. I set the DNS addresses in Network Manager as the addresses my modem-router uses, to bypass Ubuntu using my modem-router as the DNS server.

Now there is no delay in my internet connections. Websites start loading immediately, Pidgin connects immediately.