Dropbox is a great tool but, like many other Cloud services, it is far from ideal on a satellite infrastructure. There is one golden rule to using Dropbox and it is to always keep your files in the Dropbox folder even when you work on them. You should not move files in and out of the folder to work on them. Dropbox is a smart little guy and when you modify a file and save it, it will look for the differences and update only that part of the file, instead of re-uploading the whole file. This will result in less outbound traffic on the satellite and faster sync times on your end.
In your Dropbox settings, you should also disable the “LAN Sync” function. This will result in fewer broadcasts on the network and help preserve good service for the rest of your community.