Loading a large node body sequentially for better performance I have a few very large nodes on my Drupal 7 site. In some cases the body field contains about 2MB of raw HTML (about 250,000 words). Despite the site performing well as a whole, the sheer size of these nodes causes a complete page render to take about 20 seconds, both due to the amount of content being downloaded and the time it takes the browser to render that much HTML.

The only way I can see to improve performance on these nodes is to load the node body sequentially in small bits, fetching bits of HTML as the user scrolls down the page. Is something like that even possible when all the data is contained in one row in the database? Perhaps this is more of MySQL question, but I'm curious if anyone has encountered this before or has alternate solutions to this problem.
It sounds like you've hit an architecture (DBMS) constraint. I'm not aware of a way to break up a node body into segments easily (I mean i'm sure you could use a list of text fields in drupal -- but ewww).

I'm also not sure of a clean way to make the paragraphs index-able for asynchronous javascript fetching, i believe you run into issues like:
https://stackoverflow.com/questions/19477494/per-paragraph-commenting-system

What I would recommend is installing an in-memory cache like Varnish, or Memcache and storing a copy of the full page for anonymous users ... or learning Authcache for more complex scenarios.