Changing between Navigation Drawer fragments is slow

Question

I have an app with a Navigation Drawer that uses fragments for each menu item.
Each time an item is clicked, I replace the current fragment.

The problem is that it takes a long time to show the new fragment after the user clicked and it gets stuck. The fragment that takes the longest to load is a fragment that has also tabs inside it with child fragments (one fragment contains a RecyclerView).
Is there any way I can speed up the loading of the fragments? (Perhaps initializing them beforehand, if this is possible?)

Here is my code:

protected override void OnCreate(Bundle bundle)
    {
        drawerLayout = FindViewById<DrawerLayout>(Resource.Id.drawer_layout);
        navigationView = FindViewById<NavigationView>(Resource.Id.nav_view);
        drawerLayout.DrawerClosed += DrawerLayout_DrawerClosed;


        navigationView.NavigationItemSelected += (sender, e) =>
        {
            e.MenuItem.SetChecked(true);
            //react to click here and swap fragments or navigate

            switch (e.MenuItem.ItemId)
            {
                case (Resource.Id.nav_home):
                    ListItemClicked(0);
                    break;

                case (Resource.Id.nav_halachot):
                    ListItemClicked(1);
                    break;

                case (Resource.Id.nav_times):
                    ListItemClicked(2);
                    break;

                case (Resource.Id.nav_siddur):
                    ListItemClicked(3);
                    break;
                case (Resource.Id.nav_compass):
                    ListItemClicked(4);
                    break;

                case (Resource.Id.nav_settings):
                    ListItemClicked(5);
                    break;
            }


            drawerLayout.CloseDrawers();                
        };

        if (bundle == null)
        {
            ListItemClicked(0);
            navigationView.Menu.GetItem(0).SetChecked(true);
            fragment = new HomeFragment();
            SupportFragmentManager.BeginTransaction()
            .Replace(Resource.Id.content_frame, fragment)
            .Commit();
        }
    }

 public override void OnBackPressed()
    {

        if (drawerLayout.IsDrawerOpen((int)GravityFlags.Start))
        {
            drawerLayout.CloseDrawer((int)GravityFlags.Start);
        }
        else
        {
            base.OnBackPressed();
        }
    }

    private void ListItemClicked(int position)
    {

        switch (position)
        {
            case 0:
                fragment = new HomeFragment();
                Title = "Home";
                SupportActionBar.Elevation = 8;
                break;
            case 1:
                fragment = new HalachaFragment();
                Title = "aaa";
                SupportActionBar.Elevation = 0;
                break;
            case 2:
                fragment = new TimesFragment();
                Title = "bbb";
                SupportActionBar.Elevation = 8;

                break;
            case 3:
                fragment = new SiddurFragment();
                Title = "ccc";
                SupportActionBar.Elevation = 8;
                break;
            case 4:
                fragment = new CompassFragment();
                Title = "ddd";
                SupportActionBar.Elevation = 8;
                break;
            case 5:
                fragment = new SettingsFragment();
                Title = "eee";
                break;
        }



    }

    private void DrawerLayout_DrawerClosed(object sender, DrawerLayout.DrawerClosedEventArgs e)
    {
        SupportFragmentManager.BeginTransaction()
            .Replace(Resource.Id.content_frame, fragment).AddToBackStack("BACK")
            .Commit();

    }

HalachaFragment.cs (The fragment that contains the tabs):

public class HalachaFragment : Fragment
{
    private ViewPager halachotPager;
    private PagerSlidingTabStrip tabs;

    public HalachaFragment()
    {
        this.RetainInstance = true;
    }
    public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        // Create your fragment here
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        // Use this to return your custom view for this Fragment

        var view = inflater.Inflate(Resource.Layout.HalachaSection, container, false);

        var fragments = new Android.Support.V4.App.Fragment[]
       {
           new HalachotFragment(),
           new BooksFragment(),
       };

        var titles = CharSequence.ArrayFromStringArray(new[]
        {
                "הלכות",
                "ספרים",
        });

        halachotPager = view.FindViewById<ViewPager>(Resource.Id.halachotPager);

        halachotPager.Adapter = new TabsFragmentPagerAdapter(this.ChildFragmentManager, fragments, titles);
        halachotPager.OffscreenPageLimit = 2;
        halachotPager.SetCurrentItem(1, true);
        // Bind the tabs to the ViewPager
        tabs = view.FindViewById<PagerSlidingTabStrip>(Resource.Id.halachotTabs);

        tabs.SetViewPager(halachotPager);

        return view;

    }
}

Hope someone can help me.

Thanks.

Answer 1

See this solution. Just use a thread for load the fragment child. When change your onItemClick.

layoutDrawer.closeDrawer(linearDrawer);
setLastPosition(posicao);
new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            setFragmentList(lastPosition);
        }
    }, 0);