It may not be the BB that's at fault, but the "virtual circuit" between your computer and the source.
Personally I use Download Accelerator Plus which, where possible, opens up multiple links between you and the source and/ or any mirrors available and downloads file "chunks".
This means that if one link is running slow, the others take up the slack and aren't held up by the laggard.
You can download a free version from
http://www.speedbit.com