What DreamHost server are you on? I am on 'Bixel' and FTP uploads are always as fast as my connection allows.
To eliminate your computer system as a possible source of the problem, try uploading from another system to see if that resolves the problem.
In my case, it is usually my teenage daughter's system causing problems, but since she is connected via wireless and the access point is right next to me, the solution is easy.
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