It sounds like ISP interference unfortunately. It looks like they have a p2p program bandwidth shaper. As soon as it detects you using LW, it jumps into action & limits the bandwidth that LW can use. This filter will put p2p use into 3ed tier speeds ... so it doesn't affect people who just want to browse. ie: p2p uses a lot of bandwidth & nowadays in some parts of the world ISP's are over-selling their bandwidth capability ... not expecting everyone to be using their maximum potential. Game users are also often affected by ISP's.

That magnet link is from a web site, so there's no excuse for it to be downloading slowly (can potentially get over 200 KB/s from that magnet site!) I often get suspect users to do that test to see whether it might be the ISP at fault.