"has the limewire server slowed down" ?

i think there is no such thing as a central limewire server
in charge of downloads and uploads.
this is called peer-to-peer. you are in more or less direct contact
with your uploader's computer.
i don't know why your download speed has decreased so
dramatically, so consistently.
you may just be downloading from peers who have a huge upload load and therefore limit their upload speed, who are serving many peers at the same time, etc.

or your service provider may be at fault. check out your
download speed
s