I'm not completely sure on how this works.
-But I know the more users you download from the faster it will go.
-Even if you have a DSL connection, the person you are transferring from may only have a dial-up. And at the time they may be sending multiple people the file, so the bandwidth they have has to be shared.
-Another option could be that the user your downloading from is limiting the bandwidth used for uploads to other PC's.
-In another case your own program could be limiting your download speeds.
You can go here to take a speed test to see how much you really are getting from your connection: Speed Tests
As far as optimizing your connection speeds I would search the net through google. I don't know to much about this, rather than keeping your internet files cleaned out(cache, history, temporary files.)
Hope this helped.
P.S. Feel free to correct me if I'm wrong.
- Cody McEntyre