To solve the question of how Google Docs works: 

Here is a Blog post by the guy who designed the syncing system of gdocs: https://neil.fraser.name/writing/sync/

The link point to a detailed writeup of a syncing system that can work in lossy enviroment like Internet.

The whole process is just a giant diff-match-Patch cycle between clients and the Server farm(as one Server is unable to handle all load), controlled and timed by the client. If no changes are done either by client or Server, the client will slow down the process Timing.

More Details can be found in the linked document.