Paris - London - New York
@jiherr
https://www.meetup.com/React-Native-London/
(because it is)
Pick a key user journey
Use an Android test device
Plug it in your computer
Start the app
Run through the journey
adb shell dumpsys gfxinfo com.example
Janky Frames
time
Performance of key user journey
20%
https://medium.com/@addyosmani/the-cost-of-javascript-in-2018-7d8950fbb5d4
Premature optimisation is a waste of time
Do not guess which part of the code should be fixed
If you have an intuition, measure it!
If you don't have a clue, read the ... amazing manual ❤️
https://facebook.github.io/react-native/docs/performance
why-did-you-update
Chrome debugger's flame chart
React Devtools' Profiler
Firebase performance tracking
framestats
systrace
...
time
Performance of key user journey
38%
Janky Frames
time
Performance of key user journey
38%
19%
15%
Janky Frames
It is easy to stop caring...
Optimising performance is an Engineer's drug.
Make sure you often
take a step back:
Am I actually making a difference for my users?
Measure it as a team!
@jiherr
Paris - London - New York