This tweak is also valid for any windows version, and I have heard other operating systems to include Linux.
Symptom: 10 to 30 seconds delay or maybe even up to 1 minute when loading any web page. Once a web page is up, full internet speed is available, also downloads are not affected by speed loss. If you have TCP/IP version 6 installed this is highly likely the problem.
How to check if IPv6 is installed (Windows XP): Open up the control pannel. If it is titled "pick a category", click "switch to classic view." Open "Network Connections." Here there should be a list of your internet connections, they could be network cards, dial-up connections, or others. Find the one you connect to the internet with, for example "Local Area Connection #1" Right-click on its icon and choose properties. In the middle of the properties window you will see a smaller window that is titled "This connection uses the following items." Some of the common items are: "Client for microsoft networks" "Internet Protocal (TCP/IP)"
How to fix (Windows XP): In this windows if you see one of the items labeled "Microsoft TCP/IP version 6" select it and click the uninstall button. DO NOT UNINSTALL "Internet Protocal (TCP/IP)" this will disable your internet connectivity completely.
Other Notes: As far as I know this will be the next internet standard, but for now using the standard "Internet Protocal (TCP/IP)" will work. You shouldn't find any problems uninstalling IPv6. You may ask how did this get installed? IPv6 is listed in windows updates and could be installed this way. I am guessing that IPv6 slows down web connections because most web servers aren't using it yet.