Performance analysis and benchmarks

[allenporter]

Is your feature request related to a problem? Please describe.
It could be worthwhile to do some basic performance tests on very large calendars to see where the overhead is at the moment. Performance was not an initial v1 goal (e.g. streaming components/properties, etc) but worth checking in on.

Describe the solution you'd like
Unsure what the best benchmarking/performance analysis tooling is, but it may be more interesting to do with a real life example in a calendar system, rather than at the library level.

[allenporter]

We now have some benchmarks, and did some performance work on improving reuse of parsers.