Because my app is slow in transitioning from Fragment

Question

My app gets slow ( and comes crashing, but without crashing ) after I click a button that transitions from Fragment, was working normal, I went to tinker with another area of the app and when I returned, this way.

Fragment containing the onclick

public class PreparacaoFragment extends Fragment implements View.OnClickListener {
    public PreparacaoFragment() {
        // Required empty public constructor
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_preparacao, container, false);
    }

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        int[] BUTTON_IDS = {
                R.id.btndia1,
                R.id.btndia2,
                R.id.btndia3,
                R.id.btndia4,
                R.id.btndia5,
                R.id.btndia6,
                R.id.btn_exercicios
        };

        List<FancyButton> buttons = new ArrayList<>();

        for(int id : BUTTON_IDS) {
            FancyButton button = view.findViewById(id);
            button.setOnClickListener(this);
            if (id != R.id.btn_exercicios){
                button.setEnabled(false);
                buttons.add(button);
            }else{
                button.setEnabled(true);
                buttons.add(button);
            }

        }
        for (int i = 0; i < 4 ; i++) {
            buttons.get(i).setEnabled(true);
        }

    }

    @Override
    public void onClick(View view) {
        DiaFragment fragmentdiapreparacao = new DiaFragment();
        Bundle args = new Bundle();
        int[] layouts;
        switch (view.getId()){
            case R.id.btndia1:
                //SETAR LAYOUTS
                layouts = new int[]{R.layout.dia1s1, R.layout.dia1s2, R.layout.dias1s3};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btndia2:
                //SETAR LAYOUTS
                layouts = new int[]{R.layout.dia2s1};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btndia3:
                //SETAR LAYOUTS
                layouts = new int[]{R.layout.dia3s1};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btndia4:
                //SETAR LAYOUTS
                layouts = new int[]{R.layout.dia4s1};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btndia5:
                //SETAR LAYOUTS
                layouts = new int[]{R.layout.dia5s1};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btndia6:
                layouts = new int[]{R.layout.dia6s1,R.layout.dia6s2};
                args.putIntArray("layouts",layouts);
                break;
            case R.id.btn_exercicios:
                Toast.makeText(getContext(), "Atividades", Toast.LENGTH_SHORT).show();
                break;
        }
        fragmentdiapreparacao.setArguments(args);
        if (!fragmentdiapreparacao.getArguments().isEmpty()){
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.replace(R.id.contentmain, fragmentdiapreparacao);
            ft.commit();
        }

    }
}

Final fragment:

public class DiaFragment extends Fragment {
    private static final String TAG = "igr";
    private CustomViewPager viewPager;
    private PlayPauseView btn_audio;
    private FancyButton btn_prox;
    int posicaolayoutaudio;
    private int[] mlayouts;
    private int[] mlayoutslayout;
    int layoutaudioposicao;
    private ViewGroup containerdia;
    private boolean finalizar;

    MediaPlayer mPlayer;
    String url = "http://doupenglish.com.br/admin/audios/01%20Trilha%201.mp3";


    public DiaFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        mlayouts = getArguments().getIntArray("layouts");
        mlayoutslayout = getArguments().getIntArray("layoutslayout");

        return inflater.inflate(R.layout.diafragment, container, false);
    }

    @SuppressLint("ClickableViewAccessibility")
    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {

        viewPager = view.findViewById(R.id.viewpagerdias);
        viewPager.setPagingEnabled(false);
        viewPager.setOffscreenPageLimit(1);
        viewPager.setAdapter(new PagerAdapter() {
            @Override
            public Object instantiateItem(ViewGroup container, int position) {
                View view;
                LayoutInflater inflater = (LayoutInflater) container.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                view = inflater.inflate(mlayouts[position], null);

                //botão proximo
                btn_prox = view.findViewById(R.id.btn_prox);
                btn_prox.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {
                        mudarpagina();
                    }
                });

                if (mlayouts.length == 1){
                    botaofinalizar();
                }

                btn_audio = view.findViewById(R.id.btn_audio);
                final PulsatorLayout pulsator = view.findViewById(R.id.pulsator);
                mPlayer = new MediaPlayer();
                mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
                mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                    @Override
                    public void onCompletion(MediaPlayer mediaPlayer) {
                        btn_audio.toggle();
                        pulsator.stop();
                    }
                });
                try{
                    mPlayer.setDataSource(url);
                    mPlayer.prepare(); // might take long! (for buffering, etc)
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (btn_audio != null){
                    btn_audio.bringToFront();
                    btn_audio.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            btn_audio.toggle();
                            if (mPlayer.isPlaying()){
                                pulsator.stop();
                                mPlayer.pause();
                            }else{
                                mPlayer.start();
                                pulsator.start();
                            }
                        }
                    });
                }
                container.addView(view);
                return view;
            }
            @Override
            public int getCount() {
                return mlayouts.length;
            }
            @Override
            public void destroyItem(ViewGroup container, int position, Object object) {
                container.removeView((View)object);
            }
            @Override
            public boolean isViewFromObject(View view, Object object) {
                return view == object;
            }
        });
        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }
            @Override
            public void onPageSelected(int position) {
                //Log.d(TAG, "onPageSelected: "+position);
                //Log.d(TAG, "onPageSelected: "+mlayouts.length);
                if (mlayouts.length-1 == position ) {
                   botaofinalizar();
               }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

    private void botaofinalizar() {
        btn_prox.setText(getString(R.string.terminar));
        btn_prox.setIconResource("");
        btn_prox.setBackgroundColor(Color.parseColor("#3b5998"));
        finalizar = true;
    }

    private void mudarpagina() {
        if (finalizar){
            Log.d(TAG, "onClick: Entrou no finalizar");
            Fragment fragment = new PreparacaoFragment();
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.replace(R.id.contentmain, fragment);
            ft.commit();
        }else if (viewPager.getCurrentItem()  != mlayouts.length){
            viewPager.setCurrentItem(viewPager.getCurrentItem()+1);
        }

    }


    @Override
    public void onDestroy() {
        if (mPlayer != null) mPlayer.release();
        super.onDestroy();
    }
}