I looked into this further with the engineer that is working on the Uploader templates. We are basically waiting until SmugMug responds back to us that our upload was received. The delay is on SmugMug's end. Your graph shows that we're sitting idle during this time.
One way we could improve this would to be to start another file uploading while we wait for the acknowledgment. Why SmugMug is taking so long to respond is unknown to us but it may have something to do with how busy their servers are.
-Kirk
Thanks for the info, Kirk. I assumed the delay was on SmugMug's end, but it would be nice if the PM uploader could start another upload while waiting for acknowledgment, the way MacDaddy seems to. As it stands now the PM uploader is just too slow for anything other than small uploads, at least for me (and the lack of gallery creation is problem too).