Find performance bottlenecks

[twolfson]

While #14 is a step in the right direction, the benchmark of 800ms for 100 repeated requests leaves me wanting more. We should add some timing logs to each function run in the test suite.

Off the top of my head, some more possible gains might be:

• Key generation (try to use a better serializer)
  • https://github.com/isaacs/sigmund
• Caching of generated keys (avoid md5 if it is too slow)

[twolfson]

I thought I wrote this down but I guess not. Consider using object-hash for our key serialization:

https://www.npmjs.org/package/object-hash