Performance
Measured on 2026-10-05 on the maintainer's Apple-silicon Mac. Emulator and simulator numbers are not device numbers; they are useful for relative comparisons on the same machine only. Each value is the median of three runs (raw runs in the JSON files); per-call values are averages over a timed loop after a warm-up.
Flutter on Android — profile mode, API 37 arm64 emulator#
examples/flutter/android_slice/integration_test/bench_test.dart (flutter drive --profile), JSON: perf-2026-10-05-flutter-android.json
| Operation | Generated binding (JNI) | Hand-written MethodChannel |
|---|---|---|
Instance call returning int (Bundle.size()) |
1.00 µs | 270.7 µs |
Static call returning an object (Uri.parse) |
4.06 µs | — |
String in + string out (Uri.parse(s).toString()) |
12.50 µs | 279.5 µs |
| No-op round trip | — | 267.2 µs |
Java → Dart callback, synchronous (Handler.dispatchMessage → Handler.Callback) |
130.47 µs | — |
Handler.post on the main Looper → Dart Runnable runs (median) |
28.0 ms (sync) / 29.2 ms (async) | — |
The Handler.post latency is dominated by when the main Looper dispatches the message in this setup (the synchronous and asynchronous callback variants are the same), not by the binding call itself.
Flutter on iOS — debug (JIT), iPhone 17 simulator, iOS 26.4#
Flutter supports profile/release builds only on physical iOS devices, so these are JIT numbers. examples/flutter/ios_slice/integration_test/bench_test.dart, JSON: perf-2026-10-05-flutter-ios.json
| Operation | Generated binding (objc_msgSend) |
Hand-written MethodChannel |
|---|---|---|
Instance getter returning NSInteger (UIView.tag) |
34.4 ns | 20.4 µs |
Class getter returning an object (NSProcessInfo.processInfo) |
197.1 ns | — |
NSString set + get + convert (UIViewController.title) |
1.08 µs | 19.6 µs (echo) |
Struct by value get + set (UIView.frame) |
117.4 ns | — |
| No-op round trip | — | 26.0 µs |
React Native — release (Hermes bytecode)#
examples/react-native/slice/src/bench.ts, run after the self-tests by tools/run_rn_device_tests.sh / tools/run_rn_ios_tests.sh.
Android (API 37 arm64 emulator), JSON: perf-2026-10-05-rn-android.json
| Operation | Generated binding (JSI → JNI) |
|---|---|
Instance call returning int (Bundle.size()) |
1.50 µs |
Static call returning an object (Uri.parse, then release()) |
4.53 µs |
Call returning a string (Uri.toString()) |
1.88 µs |
Promise variant (Bundle.sizeAsync()), JNI on a worker thread |
424 µs |
iOS (iPhone 17 simulator, iOS 26.4), JSON: perf-2026-10-05-rn-ios.json
| Operation | Generated binding (JSI → Objective-C++ → NSInvocation) |
|---|---|
Foundation getter returning NSUInteger (activeProcessorCount, JS thread) |
1.14 µs |
Class getter returning an object (NSProcessInfo.processInfo, then release()) |
2.33 µs |
Getter returning a string (processName) |
0.90 µs |
UIKit getter (UIView.tag, synchronous hop to the main thread) |
9.98 µs |
UIKit struct get + set (UIView.frame, two main-thread hops) |
20.68 µs |
Promise variant (NSFileManager.fileExistsAtPathAsync) |
11 µs |
No hand-written React Native module was benchmarked for comparison.
Byte transfers (TRD §36) — single runs#
JSON: bytes-2026-10-05.json. Each value is the mean of 10 iterations after one warm-up (a single run, not a median of three).
| Path | 1 MB | 16 MB |
|---|---|---|
Flutter Android (profile, emulator): Uint8List → byte[] → Arrays.copyOf → Uint8List (byteArrayOf / bytesOf) |
1.80 ms | 32.9 ms |
| Same through a hand-written MethodChannel | 9.02 ms | 53.8 ms |
Flutter Android: fill a direct ByteBuffer (directBufferOf, then a zero-copy asUint8List view) |
2.33 ms | 5.99 ms |
Flutter iOS (debug, simulator): nsDataFromBytes (one copy) |
0.076 ms | 2.47 ms |
Flutter iOS: nsDataView (zero-copy view) |
0.0002 ms | 0.0002 ms |
Flutter iOS: NSData.toList() (copy) |
0.21 ms | 2.08 ms |
React Native Android (release, emulator): Uint8Array → byte[] → Arrays.copyOf → Uint8Array |
1.61 ms | 30.9 ms |
React Native Android: same with number[] (element by element) |
99.6 ms | — |
React Native iOS (release, simulator): nsDataFromBytes + bytesFromNSData |
0.153 ms | 1.75 ms |
Memory and callback latency (WP7) — emulator / simulator#
JSON: perf-2026-10-05-wp7.json.
| Measurement | Value |
|---|---|
Flutter Android (profile): RSS per live generated handle (Bundle), 50k handles after a warm-up, median of 3 runs |
216 bytes (runs: 216, 470, 216) |
Flutter iOS (debug): RSS per live NSOperationQueue handle (Dart wrapper + native object), 50k, 3 runs |
906 / 923 / 930 bytes |
React Native Android (release): PSS per live Bundle handle, 10k handles, single run |
46 bytes |
React Native Android: Handler.post → JS Runnable (async callback), median of 200, single run |
125 µs |
React Native iOS (release): NSOperationQueue block (background thread) → JS, median of 200, single run |
13 µs |
Flutter Android's Handler.post → Dart latency (median 46653 µs over the 3 runs) is dominated by when the main Looper runs the posted message during frame work in profile mode, not by the binding call; React Native's JS thread is separate from the main thread, so its posted callbacks arrive faster.
Not measured yet#
Physical devices (none measured: no consent was given to install on the attached phone); release-mode Flutter on iOS (the simulator supports debug only).
docs/benchmarks/performance.md