startup-jank-profiler

Measure cold startup with a Macrobenchmark test using StartupTimingMetric and StartupMode.COLD, running 5-10 iterations on a real device. Always benchmark the release build with R8 enabled, since debug builds are not representative of production performance.

A Baseline Profile is a generated list of classes and methods the ART runtime pre-compiles, typically improving cold start by 15-30%. Add the androidx.baselineprofile plugin, write a generator test that exercises startup and key user paths, and ship the profile with the app.

LazyColumn jank usually comes from missing item keys, causing every item to recompose on data change. Add items(list, key = { it.id }), move image decoding to Coil or Glide, and avoid heavy synchronous parsing during scroll.

Always profile release builds, because R8 minification and resource shrinking significantly change startup behavior. Use a profileable manifest entry if you need tracing on a non-debuggable build.

Do not move work to a background thread if it must complete before the first frame renders, since that creates a race condition rather than a fix. Only defer SDKs and services that the first screen does not need, using androidx.startup or Dispatchers.Default.