Uploading to SmugMug very slow...suggestions?

I've recently started using SmugMug as an online backup for my pics, as well as to provide a platform for sharing images with friends and family. So far really happy with it, though haven't even started to use it to its full potential. The one headache that I'm having though is the really slow upload speeds. As a rough estimate these are probably a quarter of the speed that I get compared to uploading to other applications like dropbox, or when sending large attachments via MS Outlook.

I have tried different options such as using Google Chrome rather than Internet Explorer, or downloading the SmugMug upload plug-in for Windows Explorer, but it doesn't seem to make much of a difference.

Has anyone else had a similar headache and are there any suggestions on how to improve upload speed? Or is this just something you have to live with when using this particular platform?