Try to download a file from here & see what speeds you get
http://www.magnetmix.com/video.shtml

Has anything changed since your speed dropped (ISP plan, hardware, LW version etc)?
Do a speed test & tell us the result:
http://www.dslreports.com/speedtest?more=1

Had you been doing some heavy downloading before the speed drop?
What are your details?

OS(Win XP etc)
LW & Java version (help > about LW & you'll see)
Firewall you're using
Modem/router brand & model
ISP
Connection type (DSL etc)
Where you connect from (home, school, student accommodation etc)
Are you sharing a connection with other computers
Is this your first try with LW
Have you tried other p2p apps & if so, do you have the same problem