title: Android Firebase: signInWithCustomToken takes a very long time
body: <p>Attempting to sign into Firebase using a custom token on Android takes roughly 30 seconds to complete on average. It's not a network issue as the call to my server to get the custom token returns in a very short amount of time. This is using the latest 10.0.1 version for each Firebase library. Here is the relevant code:</p>
  
  <pre><code>String customToken = //retrieved from server
  
  firebaseAuth.signInWithCustomToken(customToken).addOnCompleteListener(new OnCompleteListener&lt;AuthResult&gt;() {
  
      @Override
      public void onComplete(@NonNull Task&lt;AuthResult&gt; task) {
  
          //30 seconds later, task is successful
  
  
      }).addOnFailureListener(new OnFailureListener() {
  
      @Override
      public void onFailure(@NonNull Exception e) {
          Log.d("error", "failed to sign in with custom token " + e.getLocalizedMessage());
      }
  });
  </code></pre>
  
  <p>I know that the custom token is valid because the operation eventually succeeds, but not after hanging for 30 or more seconds. Needless to say, that kind of performance is unacceptable in a production app.</p>