pauses during song playback in Raspberry Pi

I'm programing a playlist player in python using spotify and is running in Raspberry Pi. Everything is great just the songs have pauses during the playback. I done everything, update, check de ALSA driver, the code, I overclocking the raspberry, change the output between analog/HDMI, prefetch the song, but just still having pauses.

What am I doing wrong?

def player(session):

    end_of_track = threading.Event()
    global volume_effect

    track = tracks[0]

    def on_end_of_track(self):
        end_of_track.set()

    session.on(spotify.SessionEvent.END_OF_TRACK, on_end_of_track)
    logger.info('End Track Event On')

    session.player.prefetch(track)
    session.player.load(track)
    session.player.play()

    logger.info('Playing: %r and %r', track.name, track.duration)

    tracks.rotate(1)

    logger.info('Next Song: %r', tracks[0].name)

    if volume_effect == False:
            for v in range(volume_min, volume_max, 5):
                    mixer.setvolume(int(v))
                    time.sleep(2)

            volume_effect = True

    try:
            while not end_of_track.wait(track.duration/1000):
                    pass
    except KeyboardInterrupt:
            pass
    else:   
            end_of_track.clear
            session.player.unload()
            player(session)