[TeMPOraL]

Did Babel contributors put much effort into optimization? JS isn't exactly high-performance by default.

[hzoo]

We certaintly have PRs around perf https://github.com/babel/babel/labels/area%3A%20perf but we don't have explicit benchmarking for it, and have had work from v8 team and others https://twitter.com/rauchg/status/924349334346276864?s=20.