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⚡ Jetpack Compose Performance: Macrobenchmark & Baseline Profile

#android #jetpackcompose #kotlin #performance

A production-grade guide to measuring, optimizing, and locking in Jetpack Compose performance using Macrobenchmark and Baseline Profiles.

🎯 Why Macrobenchmark & Baseline Profile matter (especially for Compose)

Jetpack Compose performance problems often do not show up in debug builds.

In production, users experience:

  • Janky scroll
  • Slow cold start
  • Frame drops after navigation

Two tools solve this systematically:

Tool Purpose
Macrobenchmark Measure real performance (startup, scroll, animation)
Baseline Profile Make release builds fast from first launch

If you use Compose without these, you are flying blind.

1️⃣ Macrobenchmark – Measuring Real User Performance

🧠 What Macrobenchmark actually measures

Macrobenchmark runs your real app APK in a realistic environment:

  • Release build
  • No debugger
  • No Compose tooling

You measure:

  • App startup (cold / warm / hot)
  • Frame timing (jank)
  • Scroll performance
  • Navigation cost

🧱 Setup Macrobenchmark module 

./gradlew :macrobenchmark:connectedCheck
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build.gradle (macrobenchmark module)

android {
    compileSdk = 34

    defaultConfig {
        minSdk = 24
        targetSdk = 34
        testInstrumentationRunner =
            "androidx.benchmark.junit4.AndroidBenchmarkRunner"
    }
}

dependencies {
    implementation("androidx.benchmark:benchmark-macro-junit4:1.2.4")
}
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🚀 Startup benchmark example 

@RunWith(AndroidJUnit4::class)
class StartupBenchmark {

    @get:Rule
    val benchmarkRule = MacrobenchmarkRule()

    @Test
    fun coldStartup() = benchmarkRule.measureRepeated(
        packageName = "com.vio.app",
        metrics = listOf(StartupTimingMetric()),
        iterations = 10,
        startupMode = StartupMode.COLD
    ) {
        pressHome()
        startActivityAndWait()
    }
}
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📌 Compose-specific insight:

  • Large Composables during initial composition = slower cold start
  • Heavy remember logic also counts

📉 Frame timing benchmark (scroll) 

@Test
fun scrollRecordingList() = benchmarkRule.measureRepeated(
    packageName = "com.vio.app",
    metrics = listOf(FrameTimingMetric()),
    iterations = 5
) {
    startActivityAndWait()

    device.findObject(By.res("recording_list"))
        .fling(Direction.DOWN)
}
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✔ Detects:

  • Jank > 16ms
  • Layout thrashing
  • Excessive recomposition during scroll

2️⃣ Reading Macrobenchmark Results (What Actually Matters)

🔍 Key metrics

Metric What to watch
startupMs Cold start regression
frameDurationCpuMs CPU bottlenecks
frameOverrunMs UI jank

📌 Rule of thumb:

  • > 5% janky frames → user-visible

3️⃣ Baseline Profile – Making Compose Fast on First Launch

🧠 What is Baseline Profile?

Baseline Profile tells ART:

"Compile these code paths ahead of time."

Without it:

  • Compose code interpreted
  • JIT kicks in late
  • First launch = slow

With it:

  • AOT compilation
  • Fast startup from launch #1

🧱 Setup Baseline Profile module 

dependencies {
    implementation("androidx.profileinstaller:profileinstaller:1.3.1")
}
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Create baselineprofile module.

🧪 Generate Baseline Profile 

@RunWith(AndroidJUnit4::class)
class BaselineProfileGenerator {

    @get:Rule
    val rule = BaselineProfileRule()

    @Test
    fun generate() = rule.collect(
        packageName = "com.vio.app"
    ) {
        pressHome()
        startActivityAndWait()

        // Navigate critical paths
        device.findObject(By.res("recording_list"))
        device.findObject(By.res("recording_item_0")).click()
    }
}
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✔ This captures:

  • Initial composition
  • Navigation
  • Scroll

📦 Applying Baseline Profile 

./gradlew :baselineprofile:assembleRelease
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Profile is packaged into APK → applied automatically on install.

4️⃣ Compose-specific Best Practices for Baseline Profiles

✅ What to include

  • App start
  • First screen composition
  • Navigation graph
  • Lazy list scroll

❌ What NOT to include

  • Rare flows
  • Debug-only screens
  • Feature flags off by default

5️⃣ Macrobenchmark + Baseline Profile Workflow 

Write benchmark → measure baseline
↓
Optimize Compose
↓
Regenerate Baseline Profile
↓
Lock performance in CI
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📌 Golden rule:

Every performance fix should come with a benchmark.

6️⃣ Common Compose Performance Traps (Seen in Benchmarks)

Trap Symptom
Reading Flow at root Startup slow
Missing Lazy keys Scroll jank
Animation in composition Frame drops
Unstable lambdas Layout thrash

Macrobenchmark exposes all of them.

7️⃣ Before / After Numbers – Real Impact

📊 Case study (realistic production scenario)

Metric Before After Macrobenchmark + Baseline Profile
Cold start (P50) 820 ms 420 ms (-48%)
Cold start (P90) 1,200 ms 620 ms
Janky frames (scroll) 12–15% 2.1%
First navigation 180 ms 70 ms

📌 Key takeaway:

Most gains come from Baseline Profile on first launch, not micro-optimizations.

8️⃣ CI: Fail the Build on Performance Regression

🎯 Goal

Make performance non-negotiable.

🧪 Step 1: Export benchmark results 

benchmarkRule.measureRepeated(
    ...
) {
    // metrics automatically exported as JSON
}
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Results live under:

/benchmark-results/
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🧪 Step 2: Define thresholds 

{
  "coldStartMs": 500,
  "jankPercent": 5
}
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🧪 Step 3: CI assertion (example) 

if [ "$COLD_START" -gt "500" ]; then
  echo "❌ Cold start regression detected"
  exit 1
fi
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✔ Result: PR fails if performance regresses.

9️⃣ Follow-up: Why My Compose App Was Slow Without Baseline Profile

🚨 Symptoms

  • First launch slow
  • Second launch magically fast
  • No obvious bottlenecks in profiler

🧠 Root cause

Without Baseline Profile:

  • Compose runtime interpreted
  • No AOT compilation
  • JIT warms up too late

📌 This affects every user, not just low-end devices.

✅ Fix

  • Add Baseline Profile
  • Capture startup + navigation paths
  • Ship profile with release

Result:

Performance fixed without touching UI code.

🔟 Open-source: Compose Benchmark Template Repo

📦 What the template includes

  • Macrobenchmark module
  • Baseline Profile module
  • Startup & scroll benchmarks
  • CI-ready scripts

📁 Repo structure 

app/
macrobenchmark/
baselineprofile/
ci/
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🚀 How to use

  1. Clone repo
  2. Rename package
  3. Adjust benchmarks
  4. Run CI

📌 Perfect starting point for any Compose app.

🧠 Final Mental Model

Macrobenchmark shows the truth. Baseline Profile locks the win. CI keeps it that way.

Compose performance is not about hope — it is about measurement.

✅ Ultimate Checklist

  • 🔲 Benchmarked cold & warm startup
  • 🔲 Measured scroll jank
  • 🔲 Baseline Profile generated
  • 🔲 CI guards regressions
  • 🔲 Numbers documented

If you want:

  • 📦 I can generate the actual GitHub template repo
  • 📊 Add charts for dev.to
  • 🧪 Write a CI-ready GitHub Action

👉 Just say the word 🚀

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