My ISP decided to throttle me which is one reason it was so slow for me. I then decided to try the protocol encryption to prevent my ISP from identifying I was connected to a torrent. After doing this my download speed jumped from 10kB/s to 50kB/s.
From the Bit Torrent Help files:-
\"4. Enabling Protocol Encryption
Some ISPs (Internet Service Providers) actively interfere with P2P activities in order to reduce their bandwidth requirements. This causes BitTorrent and other file sharing download speeds to become slow. To avoid this, BitTorrent and other clients have introduced an encryption protocol to prevent ISPs from identifying BitTorrent traffic.
- Go to Options > Preferences > BitTorrent. Set Outgoing under Protocol Encryption to Enable, check \"Allow incoming legacy connections\".
Some ISPs have extremely aggressive throttling methods and for those users it might be necessary to set outgoing to Forced; however this will greatly reduce the number of peers you can connect to. Enabled is sufficient for most users.
Hope that might help.