I've been using a usenet client for about 3 years called UseNext, its pretty cool, makes nice folder for me etc lets me know what I have already downloaded previously etc, and I pay a subscription to download from their servers. I get really good download speeds from their servers, like at least 100 kbps.
Lately I noticed my download speeds were stuck between 1 and 10 kilo bytes per second. I just gave them a ring to ask if they were deliberately throttling traffic on the ports or protocols that are used by Usenet (so this would affect any usenet client you might be using) and they didn't seem to think there was any throttling in place at all for usenet traffic.
Has anyone else on Slingshot experienced similar issues?