[SOLVED] React Native "dropped so far" perf monitor count constantly increases

Issue

I originally noticed this issue in my completed app, but have installed the default react-native app to test, and I’m seeing the “dropped so far” number in the perf monitor constantly creep up even though nothing is happening.

Is this number supposed to increase constantly?

dropped so far

Solution

So based on Michael Cheng’s answer I delved into the RN code a bit more, and dug out EXPECTED_FRAME_TIME which is set to 16.9, a-la the classic 60fps magic number.

The reason the dropped frames counter was constantly (i.e continually) increasing was that RN expects to run at 60fps and thinks any framerate less than this means dropped frames.

however, having tested this particular tablet with various “framerate” testing apps, the tablet’s native framerate appears to be 51.9fps. I don’t know why that is, it seems a particularly arbitrary number, but in all my testing the framerate never went above 52 and mostly hovered at 51.

So to answer my question, “dropped so far” means how many frames have been less than 60fps, and “should it increase continually?”; yes if the device is only capable of drawing less than 60fps anyway.

Answered By – Dave Irvine

Answer Checked By – Marilyn (BugsFixing Volunteer)

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