"TCP Receive Window"? "Path MTU Discovery"? "Black Hole Detection"? If those terms mean anything to you, you can grab Dr. TCP to tweak those settings on your legacy Windows PC (XP and earlier). You can find instructions on how to do so in the old, but solid, PCWorld article Unclog Your Net Access for Fast Relief.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.