🚀 Stop Slowing Down Your App: How Delayed SDK Initialization Boosts Performance

Dec 4, 2025

A Practical Strategy to Improve Cold-Start Performance

Modern mobile apps rely on dozens of SDKs to deliver analytics, messaging, personalization, and other essential services. However, when all of these SDKs initialize during app startup, they place a heavy burden on the device — especially on low-end hardware or unstable networks. As a result, users often experience sluggish cold starts and delayed interaction.

To address this, we propose a pragmatic, production-ready strategy: delayed SDK initialization for Amplitude, Braze, and other heavy analytics or engagement SDKs. Instead of starting these SDKs immediately, you initialize them only after the app reaches a stable state.

Consequently, you avoid early competition for CPU, I/O, and bandwidth. This leads to faster cold starts, smoother first-run experiences, and reduced startup network congestion — all without sacrificing core analytics or messaging functionality.

🎯 Goal

Provide a clean, realistic strategy to improve app startup performance by deferring heavy SDK initialization until the moment your app actually needs them — usually after the user lands on the Home screen or after onboarding is completed.

This reduces:

CPU spikes at app launch
startup network storms
UI jank during the first seconds of use
cold-start times on poor networks or low-end devices

The outcome: better perceived performance, without losing analytics or messaging capability.

delayed SDK initialization

⚠️ Why Startup Slows Down

And why SDKs are often the culprit

When the app process boots, the OS is still allocating memory, setting up threads, and bringing your UI to life. During this process, the application starts multiple requests to your own servers to handle things like authentication. At that same moment, many SDKs:

run class initializers
touch disk / local storage
spawn background threads
perform network handshakes
fetch experiments, configs, or user profiles

When 3–5 SDKs do this at once, startup becomes congested.

Typical symptoms include:

⏳ Long time-to-interactive (TTI)
😵 First-screen jank or stutter
📉 Increased likelihood of crashes/ANRs during launch
📡 Several simultaneous network calls competing for bandwidth

Research and platform guidance (especially on Android) consistently confirm the same point: deferring non-critical work is one of the most impactful cold-start optimizations available.

📉 Network & Bandwidth Impact

Several studies and case reports show:

Reducing network calls during startup improves load time dramatically under 3G/4G and limited Wi-Fi.
Apps that defer unused SDKs see 30–60% cold-start improvements in real conditions.
Local caching and lazy initialization reduce the number of network round-trips needed during the first seconds.

Amplitude, Braze, and other vendors also document ways to control initial network activity.

🧩 What SDKs Do at Startup

Amplitude (default behavior)

On init, Amplitude typically:

Reads device/user IDs
Spins up event-processing threads
Loads and writes disk-backed queues
Optionally fetches config & experiment variants
Starts buffering and sending queued events

Braze (default behavior)

The initialization can trigger:

SDK setup & configuration
Session management startup
Background workers
Content Cards / In-App Message refresh
Push token registration
User profile sync

Braze is known to perform meaningful synchronous work up front — which compounds when other SDKs do the same.

Combined impact

Initializing Amplitude + Braze + others at launch causes:

Multiple parallel network requests
CPU & I/O spikes
Visible UI slowdown
Bigger risk of startup failures in poor connectivity

This is exactly what we want to avoid.

🌟 The Proposed Strategy

Delay Initialization Until the App Is Ready

Instead of initializing analytics and engagement SDKs in:

Application.onCreate() (Android)
application(_:didFinishLaunchingWithOptions:) (iOS)

…we delay initialization until a predictable, safe moment, such as:

When the Home screen becomes visible
After onboarding is completed
After a network connection is confirmed
After first meaningful render

Benefits:

Faster cold-start time
Smoother UI on first screens
Reduced startup network congestion
Better experience in low-connectivity scenarios

🛠 SDK Support for Delayed Initialization

Braze

Braze provides official APIs for delayed initialization, such as:

enableDelayedInitialization / disableDelayedInitialization.

Android reference + iOs reference

Amplitude

Amplitude allows controlling startup behavior via:

Initializing the client at a later point in the session. This behavior varies from one platform to the other. But you decide when to Configure the SDK.
It’s also possible to optOut of tracking until the user give us permission, which can happen further during the session. Android, iOS

Recommendation

Always use vendor-provided delayed-init mechanisms when available — they handle internal edge cases.

🧭 Implementation Framework

Below is a cross-platform, practical guide.

Braze

Android

1. Configure XML (res/values/braze.xml):

To access the code ready to copy and paste, see the link attached to the image.

2. Update Application Class:

To access the code ready to copy and paste, see the link attached to the image.

iOS

1. call Braze.prepareForDelayedInitialization() as early as possible—ideally inside or before your application(_:didFinishLaunchingWithOptions:)

To access the code ready to copy and paste, see the link attached to the image.

Braze.prepareForDelayedInitialization(pushAutomation:) accepts an optional pushAutomation parameter. If set to nil, all push automation features are enabled, except requesting push authorization at launch.

How It Works

Braze stays dormant during app startup
Critical app network calls complete without competition
After 2 seconds, Braze activates and sends cached events (In the example, you can control it)
Zero data loss – events are automatically cached with CACHE_EVENTS mode (on Android)

Amplitude

1. Simply delay the SDK configuration process until a specific point on your app, and optionally opt out your user of tracking entirely (you should change the optOut key to false when you consider it’s the optimal point)

Android

To access the code ready to copy and paste, see the link attached to the image.

iOS

To access the code ready to copy and paste, see the link attached to the image.

⚖️ Trade-offs & Edge Cases

You may encounter:

🟡 Early events delayed/lost

Solution: queue in-memory or persist to disk until the SDK is ready.

🟡 Push notifications require special consideration

Braze push automation may require early setup — test carefully.

Option: initialize only the push-related components early.

🟡 Background launches (push open, deep links)

Ensure your fallback logic can initialize SDKs even when no UI is shown.

📊 What to Measure

To validate improvements, measure both before and after:

Cold-start time (process start → first frame)
Time-to-interactive (first frame → stable UI)
Number and size of startup network requests
Queue reliability for pre-init events
Performance under throttled networks

🧪 Testing Framework

Test under:

3G/Edge throttled networks
Low-end hardware
First-run and repeat-run scenarios
Background launches and deep links
Push notification flows
Experiment/feature flag fallback behavior

🏗 Proposed Architecture

Sequence Diagram (high-level)

💬 Ready to Improve Your Startup Performance?

Optimizing SDK load timing is a low-risk, high-reward tactic that many teams overlook. By implementing delayed SDK initialization, you reduce friction during cold start and ensure your most important user journeys begin smoothly.

Want help applying this strategy in your app or need a second opinion on your SDK architecture?