Parsoid implements several optimizations to speed up re-rendering tasks by reusing previous HTML and data-parsoid content. RESTBase does not yet properly implement this. It basically fell through the cracks after being touched on in T75955.
- pass the previous revision's HTML + data-parsoid to Parsoid
- pass the //current// revision's HTML + data-parsoid
- signal whether images or templates need to be updated (from header info)