This experiment is for using an image link for outside hosting to reveal that steemit grabs the image and interjects itself as the host instead of the external service, but uploading images directly as you describe may have some different implications. I am not sure how comment threads tie together with post size, but if you are having bandwidth limitation problems the post I made last year about that may help: 
[how-to-use-less-bandwidth-on-steem-to-avoid-bandwidth-limitation](https://steemit.com/steem-help/@alphacore/how-to-use-less-bandwidth-on-steemit-to-avoid-the-bandwidth-limitation-problem)