A chat screen built with React Native is slow on iOS. How do you separate whether the bottleneck is JavaScript rendering, calls across the native boundary, or a native module?
First watch the JS thread FPS and UI thread FPS separately in the Perf Monitor to see which one drops. If JS drops, use the Hermes profiler in React Native DevTools to see which component render or JS function takes long; if UI drops, use Xcode Instruments Time Profiler on the native module or view hierarchy cost; and for the boundary between the two threads, count call frequency and payload size in logs to catch serialization cost.
Performance and debuggingShort answerBasics
All you've got is vague feedback that "the app is slow." How do you approach that with…
#profiling
Performance and debuggingShort answerBasics
You're asked to "optimize this function, it's slow." What do you do before you touch the…
#profiling
Performance and debuggingMultiple choiceIntro
You want to measure app performance as the basis for optimization. Which are correct…
#profiling
Performance and debuggingShort answerBasics
Reviews of your shipped iOS app say it occasionally stops responding to touch for a few…
#profiling