If it happens over a long period of time and the trend exists with other torrents, your ISP has probably throttled your port. Might want to try changing it to see what happens.
my isp slows torrents down during the day. at night time they get real fast.
thats the problem, or its to do with the settings ^
they are seriously cracking down on illegal downloads though. peerguardian is a good thing to have. im just curious how else i could protect myself...?