benchmark

It'd be neat to have a benchmark to test our diffing needs — perf is a feature, and we should be able to catch regressions.

Given this would need to run in the browser, we'd probably need some tooling around this. I was thinking it'd be cool to run a headless Chrome instance through [puppeteer](https://github.com/GoogleChrome/puppeteer), and use the [nanobench](https://github.com/mafintosh/nanobench) module to perform the benches. Would be neat if we could run it as a standalone CLI thing, with similar output to TAP.

But by all means — feel free to pick up this issue, and run with it. Probably worth picking up similar benches as in https://github.com/choojs/choo/issues/492.

Hope this makes sense. Thanks!