Benchmark performance against async

[cjihrig]

See comparison here - https://github.com/mcollina/fastfall

[arb]

You want just like a one run kind of thing and post the result in here or is this something you'd want to maintain?

[cjihrig]

I'm not looking to maintain a test suite. Maybe some code and steps to reproduce so that we can quantify whether we've actually improved on async or not. Probably could keep all of this in a documentation directory. If the tests end up being simple to maintain then maybe it wouldn't hurt. They aren't likely to change often.

[cjihrig]

@arb I've changed my mind. We definitely do need a suite of some sort. async recently came up with one. We could use that or use whatever your heart desires.