Could be a few things. You may have a firewall blocking utorrent such as windows firewall or from your antivirus software, could be low amount of seeders for the torrents you choose. You may need to open the port in your router (consult your network setup wizard), you may have a slow network card, you may have other programs running on your computer or other users on your network hogging bandwidth. You may be using wireless? All of these things will slow down your torrent