Replace Firebase Analytics: faster cold start

Q: How do I measure cold start before / after?

iOS: Xcode Organizer's Launch Time metric (aggregate from real users) or Instruments → App Launch template (synthetic). Android: `adb shell am start -W /. ` or Play Console's Vitals → Startup time. Measure before removing the old SDK, after, and compare on the same device class.

Q: Does Respectlytics block the main thread on init?

No. `Respectlytics.configure(appKey:)` is synchronous but does only in-memory work (allocates the ring buffer). The network flush runs on a background dispatch queue / coroutine.

▸Example Firebase Analytics call (the "before")

swift Respectlytics

import FirebaseAnalytics

// Default Firebase event with rich per-user metadata:
Analytics.logEvent("purchase", parameters: [
    "value": price,
    "currency": "USD",
    "transaction_id": UUID().uuidString,
    "user_id": userId,
])

Heavy analytics SDKs do work at app launch — reading identifiers, initialising queues, network dispatch — that compounds visibly on lower-end devices. Respectlytics's SDK adds typically under 30ms to cold start, vs 100-300ms for Firebase Analytics's full initialisation chain.

☑Remove Firebase Analytics cleanly

1
Remove pod 'Firebase/Analytics' from Podfile (and any Firebase/Core pulled by it that isn't needed elsewhere)
2
Remove implementation 'com.google.firebase:firebase-analytics-ktx' from build.gradle.kts
3
Remove @react-native-firebase/analytics from package.json
4
Remove firebase_analytics: from pubspec.yaml
5
Remove FirebaseApp.configure() and Analytics.logEvent call sites — replace with Respectlytics.configure() and Respectlytics.track("event_name")
6
Delete the GoogleService-Info.plist and google-services.json if no other Firebase product remains in the app
7
Run ./gradlew :app:dependencies and confirm play-services-ads-identifier is no longer in the runtime classpath

⇋Firebase Analytics vs Respectlytics — faster cold start

	Firebase Analytics	Respectlytics
Typical cold-start contribution (p50)	— see tool note above	< 30ms
Initialisation work on launch	Reads IDFA/AAID, opens SQLite, spins up threads	Allocates ring buffer (RAM-only)
Number of background threads spawned	— typically 2-4	1
Synchronous I/O on init	— typical (SQLite open)	None

❓Frequently asked questions

How do I measure cold start before / after?

iOS: Xcode Organizer's Launch Time metric (aggregate from real users) or Instruments → App Launch template (synthetic). Android: adb shell am start -W <package>/.<activity> or Play Console's Vitals → Startup time. Measure before removing the old SDK, after, and compare on the same device class.

Does Respectlytics block the main thread on init?

No. Respectlytics.configure(appKey:) is synchronous but does only in-memory work (allocates the ring buffer). The network flush runs on a background dispatch queue / coroutine.

What's typical magnitude of improvement?

On a mid-range Android device, removing Firebase Analytics + AppsFlyer typically saves 100-300ms off cold start, depending on Google Play Services init state. On iOS the delta is usually 50-150ms. Effect is more pronounced on cold-start (uncached) than warm-start launches.

Does cold-start improvement actually affect business metrics?

Yes — first-session abandonment correlates with launch latency in published benchmarks. A 100ms improvement on the slowest deciles of your device distribution can show a measurable first-day retention lift.

⇢Related migration guides

Replace Firebase Analytics to speed up cold start