I’m having this issue with my Repeaters as well in ACF5. I think Elliot’s question of how much HTML and JS is on the page could be correct.
I’ve got a page with only 57 repeater rows. Each repeater has some conditional logic resulting 9400 lines of HTML. 1600 lines of that is TinyMCE and the Media Library scripts.
Has anyone else made any progress on finding a solution for this?