"If torrents are especially slow in relation to other forms of download you will probably find that your ISP is using some form of traffic shaping, you may be able to get around this by encrypting the torrent traffic if the client you are using supports this."
Exactly the reason why I was asking what ISP he's with. Traffic shaping etc. is why I recently moved from Pipex (now "manage" pretty much all traffic) to NewNet, who don't.