We actually don’t throttle FTP at all. We took a look, and things with your web server seem in order. Have you tried testing the current upload speeds from your local ISP to compare? http://speedtest.net/
You may also want to try uploading via some different FTP clients. We put together a good list of some to try here: http://wiki.dreamhost.com/FTP#FTP_Client_Software
If you continue to encounter issues, please don’t hesitate to contact our support team (http://dhurl.org/dhsupport) directly with details and we’ll investigate!