If your isp is not shaping your p2p bandwidth, then the download might just have gone a little stale. What you can do is cancel the download from the downld window, then re-select it from the search results. Also, search the topic again. You may pick up new sources. Speeds will naturally vary a little due to people's bandwidth being used up as more people downld from them.

If it continues long-term then try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.)

Else, . . . try downlding a magnet link from here http://www.magnetmix.com/video.shtml & see if the same thing happens. If it does, it points to your ISP putting a p2p shaper filter onto you. It may take a little time before it detects you & starts working & why you get good results initially but then ...