Using Firebase Cloud Messaging (FCM) for push notifications has minimal impact on app frame rate and memory. Notifications are handled by the system in the background, so your app's UI stays smooth at 60fps. However, frequent or heavy notifications can increase battery use and network data consumption.
To keep your app fast and responsive, avoid processing heavy tasks directly when a notification arrives. Instead, use background handlers efficiently and defer complex work until the app is active. Limit notification payload size to under 4KB to reduce network load and latency.
Adding FCM requires including Firebase SDKs, which can increase your app size by about 5-10MB. Use tools like Proguard (Android) and bitcode (iOS) to shrink the final bundle. The SDK does not significantly affect startup time since it initializes asynchronously.
On iOS, you must request user permission to show notifications and configure APNs certificates in Firebase. iOS handles notification display and actions differently, requiring specific payload keys. Android requires adding Firebase configuration files and setting up notification channels for Android 8.0+ to control notification behavior.
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