According to this benchmark much larger binary size, but similar performance: https://bellard.org/quickjs/bench.html

that was a while ago though.

Also, standard support is abysmal in Hermes, whereas full ES6 support is already there for QuickJS.

Hermes is ES6 compliant to my knowledge.

Not exactly by the looks of things. Kangax says 71% compliant. We tried Hermes at work and had to turn it off again because our app was crashing. That was before they implemented Proxy support, but I'm a little loathe to try it again.

https://kangax.github.io/compat-table/es6/#hermes0_7_0

My mistake, looks like some of the ES6 work is yet to be finished.