React native runs slow on ios device when remote debugger is off

Question

I run into this issue when try to run app on ios device(ipad4,ios10).
The app runs slow on device when remote debugger is off, if remote js debugger is on, then it runs pretty fine.
I also tried react-native run-ios --configuration Release, but its still slow. Don't know what's going on here.
Any idea how can I evaluate the real performance of the app ?
Many thanks.

Answer 1

Try to change the scheme in xcode: Product -> Scheme -> Edit Scheme -> Run -> Set Build configuration to Release.

Answer 2

I had a similar issue and my problem was that I was doing some extra console.log calls into the render methods and it was slowing everything down because of that. See if you have these in your code, remove them and try to run it again.

The problem was the same, with the debugger everything run great (I assume the logs were removed) and without debugger I saw the logs running in xCode. You can check the same in the console logs that are shown in xCode when you connect a simulator or device to your machine. In there, I was seeing a huge JSON object being logged every few seconds and then the log froze for some time.