Wm notes 1.15.0

Pinging @mglukhovsky (and @larkost if he wants to check my checking on pull requests and issues).
@timmaxw just talked about this with me.

This is the biggest performance improvement in this release, so we need to highlight that fact. I would say:

>  Significantly improved performance for [operations X, Y, Z -- these should be example operations] by lazily deserializing data

/cc @mlucy:
> I think all read operations will improve, but read operations that can extract part of a document from the B-tree and never send the whole thing over the network will get especially big benefits. Which read operations can extract partial documents from the B-tree like this?

-- dictated, but not read by @timmaxw