I just noticed that our matrix json serialization has a strangeness in it. The issue is that a matrix is serialized as an object with two properties.
The first property is the class name of the actual matrix. The second property is the serialized form of the matrix. Unfortunately, this serialized form is stored as a JSON string rather than a JSON object. This means that we wind up parsing matrix objects multiple times, first as the object, then extracting the string, parsing that, then possibly extracting rows as objects which contain strings which must be parsed. JSON parsing is fast, but this is perverse. I am happy to fix this along with all tests that break (shouldn't be any). I would very much like to fix this for 0.4, but it could wait. Is there anybody who depends on archival storage of JSON serialized matrices or vectors? I think I can make the format backward compatible, but would still like to know.
