Yeah thats for uncached stuff, from 6pm to 6am you get inconsistent speed (on my 4meg line it ranges from 0-140KB/s) , but still can get through a decent amount. During the day the server is totally down for uncached stuff but if you try the popular, cached stuff you will get full line-speed. So basically I leave my specialty downloads for the night and do my popular stuff during the day.
IS you will always get full speed on cached stuff and will always get less than 12KB/s on uncached.
Hope that helps