Track performance

[mstade]

This project could benefit from a suite of performance tests. Not sure what the best approach to this is; perhaps a good start would be to proxy unit tests to introduce instrumentation of tested functions. Not sure whether this is relevant or whether it's just pointless micro-benchmarking.

Some good performance tips can be found in this screencast: https://vimeo.com/68085383

Particularly the notes on binding, call/apply, and inspecting functions looking for this to see whether binding is necessary. That last point is very relevant for #11.

[mstade]

Have no idea how to track this, might revisit some other time.