Perf Monitor | BUOY Docs

Watch performance on a real device. The Perf Monitor is a live on-device HUD showing FPS, jank, CPU, and memory while you use the app — streamed to the Buoy Desktop dashboard so you can watch it full-size while you drive the phone.

Record a Run

Start recording and use the app normally. Bench tracks UI FPS, JS FPS, CPU, and memory on the real device the whole time.

Installation

flutter pub add buoy_perf_monitor

flutter pub add buoy_perf_monitor

Pure Dart — no native libraries, no FFI, no platform channels, no rebuild. Using the buoy umbrella? It's already registered. Standalone:

dart

import 'package:buoy_perf_monitor/buoy_perf_monitor.dart';

void main() {
  if (kDebugMode) registerBuoyPerfMonitor();
  runApp(const MyApp());
}

import 'package:buoy_perf_monitor/buoy_perf_monitor.dart';

void main() {
  if (kDebugMode) registerBuoyPerfMonitor();
  runApp(const MyApp());
}

Open the PERF tool from the floating dial to see live metrics and toggle the HUD.

What It Measures

FPS + jank — from SchedulerBinding.addTimingsCallback: build (Dart UI thread) and raster (GPU thread) frame timings. FPS is activity-gated: an idle Flutter app renders no frames, so the HUD shows — at rest — honest, not a fake 60.
Memory (RSS) — from dart:io's ProcessInfo.currentRss, sampled continuously even while the UI is still.
CPU — from /proc/self/stat on Android (no pure-Dart source exists on iOS yet).

Coming Soon

Benchmarking and batch reports — recorded, comparable runs with ranked reports, like the React Native Bench tool — plus Dart Top, a "what's eating the thread" profiler. Vote on the roadmap.

What's Next

Buoy Desktop — Watch the live HUD full-size on your desktop
Events Timeline — Performance in context with everything else
Network Monitor — Find the slow requests behind the jank