Listview and slow button

is my first app, and I have the problem that when you click on ListView the app as it freezes a moment and then responds, I think it's because my code is poorly optimized, how can I solve it?

package com.david.animefm2;

    import android.app.Activity;
    import android.app.Notification;
    import android.app.NotificationManager;
    import android.app.PendingIntent;
    import android.content.Context;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.graphics.drawable.Drawable;
import android.media.AudioManager;
import android.os.Build;
import android.os.Bundle;
import android.media.MediaPlayer;
import android.support.design.widget.FloatingActionButton;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.text.CollationElementIterator;
import java.util.ArrayList;

import com.google.android.gms.ads.AdListener;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import com.google.android.gms.ads.MobileAds;

import static android.R.drawable.ic_media_play;


public class MainActivity extends Activity {

    private ArrayList radios;
    private RadioAdapter adapter;
    private ListView lvRadios;
    private String url ="";
    private String txt = "";
    private MediaPlayer mediaPlayer = new MediaPlayer();
    private AdView mAdView;

    TextView texto;
    ImageView cover;
    //noti
    // Variables de la notificacion
    NotificationManager nm;
    Notification notif;
    static String ns = Context.NOTIFICATION_SERVICE;

    //Defino los iconos de la notificacion en la barra de notificacion
    int icono_v = R.drawable.animelayer;
    int icono_r = R.drawable.radioanime;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        texto = (TextView)findViewById(R.id.etRadio);
        cover = (ImageView)findViewById(R.id.cover);

        //config
        setVolumeControlStream(AudioManager.STREAM_MUSIC);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        MobileAds.initialize(this, "ca-app-pub-9173335460606469/5989305154");
        mAdView = (AdView) findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);
        mAdView.setAdListener(new AdListener() {
            @Override
            public void onAdLoaded() {
                // Code to be executed when an ad finishes loading.
                Log.i("Ads", "onAdLoaded");
            }

            @Override
            public void onAdFailedToLoad(int errorCode) {
                // Code to be executed when an ad request fails.
                Log.i("Ads", "onAdFailedToLoad");
            }

            @Override
            public void onAdOpened() {
                // Code to be executed when an ad opens an overlay that
                // covers the screen.
                Log.i("Ads", "onAdOpened");
            }

            @Override
            public void onAdLeftApplication() {
                // Code to be executed when the user has left the app.
                Log.i("Ads", "onAdLeftApplication");
            }

            @Override
            public void onAdClosed() {
                // Code to be executed when when the user is about to return
                // to the app after tapping on an ad.
                Log.i("Ads", "onAdClosed");
            }
        });

        final FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.start);
        //variables
        radios = new ArrayList<radio>();
        rellenarArrayList();
        adapter = new RadioAdapter(this, radios);
        lvRadios = (ListView) findViewById(R.id.lvRadeo);
        lvRadios.setAdapter(adapter);

        //Lista
        ListView lista = (ListView) findViewById(R.id.lvRadeo);
        lista.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView adapterView, View view, int i, long l) {
                SetUrl(i);
            }
        });

        // Inicio el servicio de notificaciones accediendo al servicio
        nm = (NotificationManager) getSystemService(ns);

        // Realizo una notificacion por medio de un metodo hecho por mi
        notificacion(icono_r, "titulo contenido", "texto contenido", "texto extendido");

        //BOTON FLOTANTE

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mediaPlayer.isPlaying()){
                    //metodo de pausa
                    mediaPlayer.stop();
                    mediaPlayer.reset();
                } else {
                    BotonReproducir();
                }
            }
        });
    }

    //Nombre y icono
    private void rellenarArrayList() {
        radios.add(new radio("Radio Vocaloid", R.drawable.radiovocaloid));
        radios.add(new radio("Radio Anime", R.drawable.radioanime));
        radios.add(new radio("Anime Layer", R.drawable.animelayer));
        radios.add(new radio("Anime Radio SU", R.drawable.radioanimesu));
        radios.add(new radio("canario", R.drawable.ic_home_black_24dp));
        radios.add(new radio("cerdo", R.drawable.ic_home_black_24dp));
        radios.add(new radio("delfin", R.drawable.ic_home_black_24dp));
        radios.add(new radio("gato", R.drawable.ic_home_black_24dp));
        radios.add(new radio("iguana", R.drawable.ic_home_black_24dp));
        radios.add(new radio("lince", R.drawable.ic_home_black_24dp));
        radios.add(new radio("lobo", R.drawable.ic_home_black_24dp));
        radios.add(new radio("morena", R.drawable.ic_home_black_24dp));
        radios.add(new radio("orca", R.drawable.ic_home_black_24dp));
        radios.add(new radio("perro", R.drawable.ic_home_black_24dp));
        radios.add(new radio("vaca", R.drawable.ic_home_black_24dp));

    };
    //Urls
    private void seturl(int i) {
        switch (i) {
            case 0:
                url= "http://curiosity.shoutca.st:8019/stream"; //Radio Vocaloid
                txt = "Radio Vocaloid";
                cover.setImageResource(R.drawable.radiovocaloid);
                break;
            case 1:
                url="http://perseus.shoutca.st:9253/stream"; //Radio Anime
                txt = "Radio Anime";
                cover.setImageResource(R.drawable.radioanime);
                break;
            case 2:
                url="http://animelayer.ru:5190/play"; //Anime Layer
                txt = "Anime Layer";
                cover.setImageResource(R.drawable.animelayer);
                break;
            case 3:
                url="http://animeradio.su:8000"; //Radio Anime SU
                txt = "Radio Anime SU";
                cover.setImageResource(R.drawable.radioanimesu);
                break;
        };

        texto.setText(txt);
        BotonReproducir();
    }

    private void SetUrl(int i){
        if(mediaPlayer!=null && mediaPlayer.isPlaying()){
            mediaPlayer.stop();
            mediaPlayer.reset();
        }
        Toast.makeText(getApplicationContext(), "posicion " + (i), Toast.LENGTH_SHORT).show();
        seturl(i);
    }

    private void BotonReproducir() {
        if (url != "") {
            try {
                mediaPlayer.setDataSource(url);
                mediaPlayer.prepare();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
            mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                @Override
                public void onPrepared(MediaPlayer arg0) {
                    //Inicia reproducción.
                    mediaPlayer.start();
                    Toast.makeText(getApplicationContext(),"Bufering...", Toast.LENGTH_LONG ).show();
                    // Lanzo la notificacion creada en el paso anterior
                    nm.notify(1, notif);
                    //fab.setImageResource(R.drawable.ic_media_play);
                }
            });
        } else {
            Toast.makeText(getApplicationContext(),"Select a rario", Toast.LENGTH_SHORT).show();
        }
    }
    //notificacion

    public void notificacion(int icon, CharSequence textoEstado, CharSequence titulo, CharSequence texto) {
        // Capturo la hora del evento
        long hora = System.currentTimeMillis();

        // Definimos la accion de la pulsacion sobre la notificacion (esto es opcional)
        Context context = getApplicationContext();
        Intent notificationIntent = new Intent(this, MainActivity.class);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);

        // Defino la notificacion, icono, texto y hora
        notif = new Notification(icon, "Holaaaaa", hora);
       // notif.(getApplicationContext(), "Old title", "Old notification content text", PendingIntent.getActivity(mContext, 0, new Intent(), 0));
        //Defino que la notificacion sea permamente
            //notif.flags = Notification.FLAG_ONGOING_EVENT;
    }


    @Override
    public void onResume() {
        super.onResume();
        Toast.makeText(getApplicationContext(),"7. onResume()", Toast.LENGTH_SHORT).show();
        nm.cancel(1);
    }
    @Override
    public void onDestroy() {
        super.onResume();
        Toast.makeText(getApplicationContext(),"7. onResume()", Toast.LENGTH_SHORT).show();
        nm.cancel(1);
    }

    public void onPause() {
        super.onResume();
        Toast.makeText(getApplicationContext(),"7. onResume()", Toast.LENGTH_SHORT).show();
        nm.notify(1, notif);
    }


}