low bandwidth and 'bullet-proof autosave and post locking'

I have very low bandwith – with previous versions my only problem was the time it took to upload. Since 3.6 and ‘bullet-proof’ etc I am constantly being told that my connection is lost and the post is being saved to my browser. When I try to upload (even when I go and find a fast wi-fi spot) all that is uploaded is the title without any content at all.
How do I turn off this frustrating, interfering ‘improvement’ or revert to an earlier version of WordPress?