What speeds did you get when you downloaded a file from magnetmix?

It may be as LOTR said, BT's shaping your bandwidth.

You could try deleting LW's preferences folder (points 2 & 3 below). LW must be properly closed. After deleting the prefs folder, you'll have to go back through tools > options & reset everything to the way you like it.
Fixes for LimeWire

Or try changing ports. In LW tools > options > advanced > firewall config. Change LW's listening port to 64049 > Apply > ok.
Any port forwarded within a router will also have to change


Have a look through the thread below for tips to optimise LW’s performance.
A few things to consider while configuring Limewire for optimal performance...