My app is slow or missing frames (metabug) #74833

This is a meta-issue to track reproducible reports of jank in Flutter apps.

If you are experiencing jank in your app:

1. Try to reproduce the problem in a test app. Either run flutter create janktest and recreate the situation you are experiencing in that app, or clone your app and delete code until you have the jank reproducing with a single .dart file.

2. File a bug and include your .dart file demonstrating the problem. If you need more than just a .dart file (for example, assets are needed to reproduce the issue, or plugins/packages are needed to reproduce the issue) then create a GitHub repository and upload the app there.
   Make sure to include the flutter doctor -v output and any logs from flutter run and flutter analyze.

3. Switch flutter to master channel and run this app on a physical device using profile mode with Skia tracing enabled, as follows:
   flutter channel master
flutter run --profile --trace-skia

   The bleeding edge master channel is encouraged here because Flutter is constantly fixing bugs and improving its performance. Your problem in an older Flutter version may have already been solved in the master channel.

4. Record a video of the performance issue using another phone so we can have an intuitive understanding of what happened. Don’t use "adb screenrecord", as that affects the performance of the profile run. Attach the video to your bug.

5. Open Observatory and save a timeline trace of the performance issue so we know which functions might be causing it. See "How to Collect and Read Timeline Traces" on this blog post:
   https://medium.com/flutter/profiling-flutter-applications-using-the-timeline-a1a434964af3#a499
   Make sure that the performance overlay is turned OFF while recording the trace.
   Attach the JSON file containing your trace to your bug. You may also wish to include a screenshot of the part of the trace showing the problem you are seeing, just so that people can see at a glance what kind of performance issue the bug is about.

6. Mention this bug in your bug, so that GitHub includes a link to it here.

Please avoid commenting on this bug. Keep each issue separate so that we can examine each specific problem individually. Having one issue that contains comments about multiple problems make the issue intractable.