bittorent is killing me

To start off, I have limited my bittorrent uploads to 1KB/s, so I don't think it can be that my upload bandwidth is choked. Basically, whenever I have my bittorrent client open, my internet browsing is SO SLOW. Even when I am downloading nothing, it's slow. Even when I am seeding nothing, it's slow. And as soon as I quit my client, browsing is back to it's fast, normal self. I have experienced this same behavior on 3 DIFFERENT computers using 3 DIFFERENT ISPs (one Time Warner cable, one with another cable service, one with Sprint aDSL). Each location has a different router and all of these computers have the proper ports manually forwarded to them by their routers (the client even confirms this). I have tried 3 different clients (Bittorrent, uTorrent, and Azureus). This behavior seems to occur reguardless of any of the factors considered above. Any help??????????

Note: Downloading non-torrent files doesn't really seem to be affected at all by the running Bittorrent client(s). I can still download from Download.com and such sites, but it takes FOREVER to navigate the site(s) just to get to the download link.