Most likely the problem is on the other end.

The thing is, it doesn't matter if your computer can process a gigabyte a second if the place you're downloading to can only do one kilobyte per second. The download can only go as fast as the slower of the two hosts can go.

Here's an example: Suppose there are some guys who are moving boxes. The first one moves the boxes to one place, and then the second one moves those boxes to where they're supposed to go. The first guy is pretty weak and can only carry one box per trip. The second guy is much stronger and can carry fifteen boxes per trip. The second guy's strength isn't going to help here because he only has one box per trip.