Performance Is a Feature
App store ratings directly reflect performance. Users delete apps that stutter, drain battery, or load slowly. On Android and iOS, performance issues manifest differently but share common root causes: excessive main-thread work, memory leaks, and unoptimised network calls.
The Main Thread Rule
The UI thread (main thread) is responsible for rendering 60 frames per second. Any operation taking more than 16ms blocks a frame and causes visible stuttering. Move all database queries, file I/O, and network requests to background threads.
// Android: Move work off main thread with Coroutines
viewModelScope.launch(Dispatchers.IO) {
val data = repository.fetchFromDatabase()
withContext(Dispatchers.Main) {
updateUI(data)
}
}Memory Leak Prevention
Memory leaks occur when objects are retained longer than needed. Common causes: static references to Activities, unregistered broadcast receivers, and infinite loops in background services. Use Android Studio Memory Profiler or Xcode Instruments to detect and fix leaks before release.