Reading data from Firebase takes a long time, even with a small data set

Question

I am currently using Firebase as an internal storage and want to get a dataset.

Using FirebaseUI-Android I receive data and adapt it as a list.

At first it seemed to me that the problem was related to the data set, but after reducing the data set to two json objects made of several simple strings, the problem persists.

Below is the code used to retrieve the data.

mDatabase = FirebaseDatabase.getInstance().getReference();
DatabaseReference myRef = mDatabase.child("events/");    
Log.d("TST", "Before Firebase");

//ListAdapter eventListAdapter;
upcomingEventsList.setAdapter(new FirebaseListAdapter<EventListModel>(getActivity(), EventListModel.class, android.R.layout.two_line_list_item, myRef) {
            @Override
            protected void populateView(View v, EventListModel model, int position) {
                Log.d("TST", "After Firebase");
            }
        });

The following are startup messages that have been set over time for the corresponding messages.

**01-10 23:18:25.113** D/TST: Before Firebase
I/Adreno-EGL: <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.AF.1....020_msm8960_LA.AF.1.1_RB1__release_AU ()
              OpenGL ES Shader Compiler Version: E031.25.03.06
              Build Date: 05/22/15 Fri
              Local Branch: mybranch10237523
              Remote Branch: quic/LA.AF.1.1_rb1.18
              Local Patches: NONE
              Reconstruct Branch: AU_LINUX_ANDROID_LA.AF.1.1_RB1.05.00.02.006.020.....NOTHING
I/OpenGLRenderer: Initialized EGL, version 1.4
D/OpenGLRenderer: Enabling debug mode 0
D/FA: Connected to remote service
V/FA: Processing queued up service tasks: 4
I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@1f008d67 time:914885804
I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@1b48d3c0 time:914885804
**01-10 23:18:28.283** D/TST: After Firebase
**01-10 23:18:28.283** D/TST: After Firebase

Is this loss approx. Is 3.5s normal or am I doing something wrong?

Why does the populateView method call twice more than once (displayed according to 2 TST: After Firebase messages)?

, , :

{end_date=1476835200, 
 title=Test, location=Test, content=Test, 
 start_date=1476835200, featured_image=Test,
 categories=[festivals, music]}

, , .

01-11 01:28:37.248 30667-30667/madebyhangar.valletta2018 D/TST: Before Firebase (before retrieval starts)
01-11 01:28:41.245 30667-30667/madebyhangar.valletta2018 D/TST: After Firebase (first retrieval finished)
01-11 01:28:41.350 30667-30667/madebyhangar.valletta2018 D/TST: SECOND PROCESS: After Firebase (second retrieval finished)