PERF.md

Performance and ANR checklist

Use this with Android Studio Profiler (CPU, Memory, Energy) on a release build when possible.

Startup

• Avoid disk I/O, network, or heavy reflection in Application.onCreate except what is required for the first frame.
• Prefer lazy initialization (e.g. feature modules, background CoroutineScope with Dispatchers.Default).
• For numeric cold/warm start targets, add Macrobenchmark (baseline-prof / Baseline Profile) in a separate :benchmark module.

Main thread

• Network and blocking I/O must use Dispatchers.IO (or appropriate workers), never the main thread.
• Do not use runBlocking on the main thread.
• Profile with CPU Profiler → Record → look for long-running methods on the main thread.

Compose

• Use Layout Inspector and recomposition counts to find unstable parameters.
• Prefer stable types for list items; use key in LazyColumn/LazyRow.

ANRs

• Monitor Google Play Console → Android vitals → ANRs after release.
• Pair with Firebase Crashlytics (non-fatal breadcrumbs) for context around slow paths.

Release vs debug

Always validate minify + shrinkResources (R8): proguard consumer rules are in app/proguard-rules.pro.