To reproduce:
- Enable Visual editor and set up Parsoid as per the instructions
- Create a page with some 10 code blocks on it.
- Populate those code blocks
- Save the page
- Go back to edit the page, note that the code blocks don't load
- Go to view then edit mode repeatedly, in other windows - the service will grind to a halt and CPU on the server will spike
No problems when creating, saving, or viewing, but when going back to edit the page the code blocks don't load.
Some form of spike happens on the CPU, based on php-fpm or Parsoid.