This blog post from a few years ago, suggests that:
The first answer is "don't run Bittorrent over Tor". We've been saying for years not to run Bittorrent over Tor, because the Tor network can't handle the load; perhaps these attacks will convince more people to listen.
Is this true even now? Is torrent traffic too much for Tor networks to handle?
Would it be considered bad form to use a torrent client over Tor?
