Hiya...
One major factor to consider is that you may be D/Ling files that are extremely popular...
And
That they may be files being shared by individuals who are simply trying to share far too many files of far too great a size...
ALL at the same time.
Hence, you are only being allowed a very small segment of their allowed UpLoad bandwidth...
Crazy, hmmm ?
There are hordes of people out there with 1M connections allowing so many sharing (Upload) slots that they end transferring each file at a slower rate than would a wise 56K modem user !!!