The reason is your sources for the downld usually. Unless your isp provider has a p2p sharing filter program to detect & filter users who use programs like LW. Ones like this one
http://www.sandvine.com/products/p2p_element.asp
See the following link & follow all the off-shoot links to find hints & extra skills to help solve your problem:
To continue files downlding (click on link)
* Try downlding a magnet link from here & see what speeds you get:
http://www.magnetmix.com/video.shtml
See Stief’s example:
http://www.gnutellaforums.com/showth...692#post138692 of what speeds you can potentially get from that magnet site.