This quote is from Google
Dependency injection frameworks can simplify the code you write and provide an adaptive environment that's useful for testing and other configuration changes.
If you intend to use a dependency injection framework in your app, consider using Dagger 2. Dagger does not use reflection to scan your app's code. Dagger's static, compile-time implementation means that it can be used in Android apps without needless runtime cost or memory usage.
Other dependency injection frameworks that use reflection tend to initialize processes by scanning your code for annotations. This process can require significantly more CPU cycles and RAM, and can cause a noticeable lag when the app launches.
Reference: https://developer.android.com/topic/performance/memory.html#DependencyInjection