Add some performance-oriented testing

[vkottler]

It would be neat to take some of the connection interfaces, and the Protocol and PrimitiveArray implementations, and come up with some benchmark tests to keep track of how well they perform over time.

For an interesting end-to-end test, we could test the echo connections (in isolated ConnectionArbiter instances) for some specified amount of time and just see how many bytes were transmitted and received by both ends.

You could just send 1024-byte payloads or something.

It will also be interesting to compare performance on the different platforms.

[vkottler]

I think we need #70 for this

[vkottler]

I think this is kind of fruitless for Python. If it's slow, it needs to call into C/C++ code for certain things instead.

That said, we implemented #70 and #77 to assist with benchmarking.

We could create some benchmarking applications for fun.

[vkottler]

We could wire up Echo connections of each type for 5 seconds and check the stats or something..

[vkottler]

Can essentially do this with: https://github.com/vkottler/conntextual.

[vkottler]

I've been using this script to stress test performance: https://github.com/vkottler/runtimepy/blob/master/perf_test.sh.

We'll need a way to sample / collect data with the program running and then store it on disk somewhere for later analysis (stream telemetry protocol)

[vkottler]

I wonder if the server command with -l / --loopback would make building something like this easier (#156).