title: Why FirebaseApp initialization is very slow,How to reduce app start time
body: <p>I am making one android app,earlier i have used gcm for push notification,right now I am trying  firebase cloud messaging  for sending push notifications.I have implemented firebase cloud messaging functionality in my app it is working fine but problem is it is taking too much time when app launches first time,please help me</p>
  
  <pre><code>build.gradle
  
  apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 23
      buildToolsVersion "23.0.2"
  
      defaultConfig {
          applicationId "com.next.fcm"
          minSdkVersion 15
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
          multiDexEnabled true
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
      dexOptions {
          javaMaxHeapSize "4g"
      }
  
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      compile 'com.android.support:appcompat-v7:23.4.0'
      compile 'com.android.support:design:23.4.0'
  
      compile 'com.google.firebase:firebase-messaging:9.0.0'
  
  }
  apply plugin: 'com.google.gms.google-services'
  </code></pre>