Are you using LW? You've posted in the Phex forum

Your download speed depends on your speed & the host(s) speed, how many hosts you're downloading from etc.
Have a look at this thread for some good tips about how to optimise LW's performance.
A few things to consider while configuring Limewire for optimal performance...

If you're convinced that all downloads have slowed down since upgrading, delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will kill all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.