I have a similar issue, although, my final html file size is just under 5MB, which is still quite large for the file type. I had accidentally exported the same file without caching, and the html file came out less than 1 MB. Since then, I have tried to duplicate the smaller html file size with no success.
I upgraded today too, and still getting a large html. What could be adding so much to it? I have tried a dozen or more exports, each with something turned off or on with no success, except for the transitions... The Liquid gave me a html file 2.5 mb, but the images doubled in size!
Any help would be great with this, Justin. Thanks!