React Native on Android has gotten way better over the last year. In general, Android phones just have worse performance than iPhones (even when they have better specs -- I'm not totally sure why) regardless of whether you're dealing with React Native or not.

Sometimes you might have to spend some time wrangling your code to get the performance results you want, but that's usually the case in building software.

Check out https://play.google.com/store/apps/details?id=st.li.listapp . It is built with Exponent/React Native and has pretty great performance. Got featured in the Play Store.