On master, I'm observing that, using Figwheel, changes to source take about 12 seconds to appear in a React Native app running in an iOS simulator, whereas with the 1.9.671 such changes take about 2 seconds.
I apologize for not having a minimal repro available. I suspect it is easily reproducible locally using a setup generated using re-natal init FutureApp (see https://github.com/drapanjanas/re-natal)
Of note: I don't have :npm-deps set. My compiler options are:
A git bisect shows that this was introduced with the change in CLJS-2212.