Improve performance on snapshot update

[Phil2812]

Currently, we are wasting too much time on a snapshot update (around 500ms per update on my machine, even for snapshots without any data changes). The wasted time may be reduced by implementing shouldComponentUpdate hooks for most components.

Also, we should be adding unique keys to component instances. I suggest using the unique object ids already present in the JSON and adding the "@ id" attribute to the TypeScript interfaces.

[Phil2812]

We might also consider using immutable.js to easily save more wasted render time in React, as it makes (deep and shallow) comparisons of snapshot elements straightforward and performant.