I resetted all settings (deleted ~/.config/deluge), tried new limits and without any limits but it's still the same. Everything else is fine: It shows the correct number of seeders and leechers and has lots of connections (about 100 and about 100 DHT knots).
Any idea what's happened? Could the new version of libtorrent (Ubuntu 12.10 ships with 0.16.3.0) be the reason for this strange behaviour?
edit: Downloading torrents with Deluge works fine (=with full speed).
edit2: Logging Deluge gave nothing but a "fontconfig warning". And: I've observed the same behaviour as described above on a second computer which I had upgraded to Ubuntu 12.10, too.
edit3: I can't believe I'm the only one with this problem

edit4: I finally gave up: Because of this issue and some other problems caused by the upgrade I switched back to Ubuntu 12.04 - and Deluge works like a charm again
