Implement a compressed chunk cache. This still needs a lot of work to figure out a good mechanism for looking up previous chunks, however at the moment when coupled with a high bulk chunk limit, it can be effective for solving lag issues.
Use simpler iterator
[Experimental] - Enable compressed bulk chunk cache.

Sort chunks a final time before sending. This gives the advantage that chunks will load as close to the player as they possibly can, and then move out, as well as increase the cache hit rate when using smaller bulk chunk limits such as the default of 5.