Just a thought... Enthusiastic torrent usage, visits to certain torrent sites (including those found by Googling "[whatever] torrent") can lead, for various reasons, to malware infestations, membership of botnets, stuff like that, making your interwebs go slow or maybe vanish altogether. Upload data rate derived from the torrent client may not be the whole story. Do you use a firewall? Have you checked for malware lately?