A nice contribution to the browser-based editor world. I enjoyed perusing the source, which looks pretty clear. There's not much UI, which is perfect for me because I've been looking for a browser-based editor to study.
Tried it on a 2,000 line text file and it caused Chrome 44 on Yosemite to time out close the tab.
Trivial CRDT implementations tend to be memory-heavy and to scale badly, especially after a long editing session. Decreasing the cost of tree traversal requires smart garbage collection, balancing and merging of nodes.
CRDT is heavy on metadata and thus requires some compression and garbage collection techniques.
In this implementation, every letter is a JavaScript object.
Performance was not an objective, I guess.
Tried it on a 2,000 line text file and it caused Chrome 44 on Yosemite to time out close the tab.