Shows a fully defined plain object is fastest. Surprisingly, even beat Array & Tuple.
Expando = object with properties added after creation.
Literal = all properties defined at creation.
Array = additional elements are pushed after creation (~Expando).
Tuple = all elements defined at creation, ie: size is constant.
Indexed object = an object who's keys are numbers. The expectation is this will be slowest as indexing into objects causes number toString() conversion.