Guide about benmarking JavaScript perf on Hermes

[cometkim]

Description

I'm doing a microbenchmark for JavaScript libraries. Specifically cometkim/unicode-segmenter#46

But I'm not sure how to do it correctly in Hermes. Is there any entry to sub-milliseconds timings? Or is there any internal or third-party tooling commonly used for tracking JavaScript performance?

[neildhar]

Hey @cometkim, we don't have built in support for sub-millisecond timestamps. The most reliable way to take such a measurement would be to repeat your benchmark many times so you get a more stable result, and then divide it by the number of iterations. If you're trying to profile performance, Hermes provides a sampling profiler, but that is also far too coarse grained for sub-millisecond measurements.

[cometkim]

Ok then, perhaps I could scale the input size to extream so operations take milliseconds.