Using Firebase Authentication adds network calls to your app for sign-in and token refresh. These calls can cause slight delays during login but do not affect frame rate during normal app use. Memory usage is minimal, typically under a few megabytes, as Firebase SDK manages user sessions efficiently. Battery impact is low since authentication happens infrequently, mostly at app start or user action.
Perform authentication asynchronously to avoid blocking the UI thread. Use Flutter's async/await to handle sign-in without freezing the interface. Cache user credentials securely to reduce repeated network calls. Show loading indicators during authentication to keep users informed. Avoid heavy UI rebuilds triggered by auth state changes; use state management to update only necessary widgets.
Adding Firebase Authentication increases your app size by about 2-5MB depending on included Firebase modules. This is moderate and typical for cloud services. Startup time may increase slightly due to Firebase initialization, but this is usually under a second. To minimize impact, initialize Firebase asynchronously and only when needed, not blocking the main app launch.
Firebase Authentication works similarly on iOS and Android with Flutter. On iOS, you must configure Apple Sign-In and enable keychain sharing for secure credential storage. Android requires Google Play Services for Google Sign-In and proper SHA-1 keys in Firebase console. Both platforms require platform-specific setup files (GoogleService-Info.plist for iOS, google-services.json for Android). Code signing and permissions differ but Firebase SDK abstracts most differences.
Likely causes include blocking the main thread during Firebase initialization or authentication calls. Also, waiting synchronously for network responses instead of using async calls can freeze the UI. Another issue could be heavy UI rebuilds triggered by auth state changes. To fix, initialize Firebase asynchronously, handle sign-in with async/await, and optimize state updates.