What's your ISP? If it is listed
here, then you may need to enable encryption (Options>Preferences>BitTorrent>Protocol Encryption>Enabled).
If it's still slow, then you may have to force the encryption and/or uncheck "Allow incoming legacy connections", which means every single connection will be encrypted. It usually won't be much better than just enablling it though.
Lastly, you may want to double-check that you've followed every single step correctly on the guide, especially if nothing changed.