Performance

Problems

• no boot
• slow tti
• crash
• freeze
• hanging
• slow response
• slow rtt
• stutter (fps)
• error (un)handled
• tearing (fps/hz)
• missing/wrong data
• abnormal ui
• high battery (cpu)
• fat binary/bundle
• high/leaky ram

Causes

• source js
  • caching
  • js lib
  • react compiler
• rn (old/new) arch
• js engine
  • (webkit/android)jsc/v8/(static)hermes
• renderer
  • fabric/skia
• modules
  • (turbo/nitro)modules
• backend
  • http (rest/gql)
  • websockets (tcp)
  • webrtc (p2p)
• starvation
  • low battery
  • power save mode
• user agent
  • blue light filter
  • magnification
• [threads]
  • hogging main
  • deadlock
  • livelock
  • race condition

Metrics

• release
  • adoption
  • crash-free sessions
  • new/retained/resurrected/inactive users
  • reviews/rating
• tti
• errors
  • (un)handled
  • stacktrace (sourcemaps)
  • events (analytics)
• renders
• fps (js/native)
  • nested views
• cpu
• ram
• network
  • rtt
  • downtime
• battery
• size
  • apk/ipa
  • js bundle
• analytics
  • events (single, series)
  • users (data, groups)
• The only metric that matters to me
• e2e screens/vids

Tools

App: __DEV__ off - Release perf optimisations on

• Debug menu > Perf Monitor
• Hermes sampling profile
• Flipper RN Debugger
  • breakpoints
  • Chrome profiler > React DevTools > Flame graph
• iOS: Xcode > Instruments
• Android: Studio Profiler
  • Systrace Perfetto

Libs

• 18Oct: https://rnfirebase.io/perf/usage
• 18Dec: https://github.com/welldone-software/why-did-you-render
• 21Feb: https://github.com/oblador/react-native-performance
• 21Mar: https://github.com/getsentry/sentry-react-native
• 21Mar: https://github.com/DataDog/dd-sdk-reactnative
• 22Jun: https://github.com/Shopify/react-native-performance
• 22Jul: https://github.com/callstack/reassure
• 22Sep: https://github.com/bamlab/android-performance-profiler

No Problem