Most ISPs don't like torrent-traffic (or traffic at all) because it costs them money for every single packet that gets transmitted. Torrent tends to end up send

Most ISPs don't like torrent-traffic (or traffic at all) because it costs them money for every single packet that gets transmitted. Torrent tends to end up sending a lot of small packets which costs the ISP more than if you would have downloaded the files from a single server. Plus customers flooding the network with tons of packets also means slower internet for others. That and the content provider thing are the main reasons some ISPs are already sending letters to heavy-torrenting users todays.