Compare Flutter's compilation modes: Debug, Profile, Release.

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Three build modes with very different behavior: Debug (default for flutter run ) — JIT-compiled, full asserts, Hot Reload ON, service protocol ON for DevTools / debugger. 10-20× slower than release. For local development. Profile ( --profile ) — AOT-compiled (like release), most optimizations on, Hot Reload OFF, service protocol ON for DevTools (profiling only, no debugger). Cannot run on emulators/simulators — real device only. For measuring real performance. Release ( --release / flutter build ) — AOT-compiled, all optimizations on (tree-shaking, minification, no asserts), Hot Reload OFF, service protocol OFF. What you ship to the App Store / Play Store. Use kDebugMode / kProfileMode / kReleaseMode from package:flutter/foundation.dart to gate code per mode. Three details that signal seniority: (1) **profile mode requires a real device** — emulators/simulators don't reflect real performance; (2) **never benchmark in debug mode** — it's 10-20x slower than release; (3) **`kDebugMode` / `kReleaseMode` / `kProfileMode`** from `package:flutter/foundation.dart` let you conditionally include logging or analytics. The classic mistake to avoid in your answer: 'release mode is just debug with optimizations' — no, **release mode uses a completely different Dart compilation pipeline (AOT vs JIT)**.