all communication is UDP .. it really depends on who you are downloading from.. sometimes it dialup speeds.. sometimes it uses all the bandwidth you have... do some testing and find the users with a good connection...
--edit--
that being said, your isp may not like fopnu so in turn you are the user with a bad connection...
..and don't forget fopnu is still being developed so stuff is very subject to change/improvement...
winmx file transfer is TCP so its like downloading something through a browser... thats where your high speeds come from..
