200+ millisecond blocking delay when calling stop() on a QSoundEffect

#include <QtGui>

#if (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
#include <QtWidgets>
#endif

#include <QtMultimedia/QSoundEffect>

class AudioPlayer : public QWidget
{
    Q_OBJECT
public:
    AudioPlayer(QWidget *parent) :
        QWidget(parent),
        mLayout(new QVBoxLayout(this)),
        mButton(new QPushButton("Play", this)),
        mLabel(new QLabel("...", this))
    {
        mLayout->addWidget(mButton);
        mLayout->addWidget(mLabel);
        setLayout(mLayout);

        mLabel->setAlignment(Qt::AlignHCenter);

        connect(mButton, SIGNAL(clicked()), this, SLOT(playPause()));

        mTimer.setInterval(5);
        mTimer.start();
        connect(&mTimer, SIGNAL(timeout()), this, SLOT(animate()));

        resize(parent->width(), parent->height());
    }
private slots:
    void playPause() {
        if (!mSound.isPlaying()) {
            mSound.setSource(QUrl::fromLocalFile("test.wav"));
            mSound.setLoopCount(QSoundEffect::Infinite);
            mSound.setVolume(0.25);
            mSound.play();

            connect(&mSound, SIGNAL(loadedChanged()), this, SLOT(doneLoading()));

            mButton->setEnabled(false);
            mButton->setText("Stop");
        } else {
            QElapsedTimer elapsedTimer;
            elapsedTimer.start();
            qDebug() << "Before QSoundEffect::stop()";
            mSound.stop();
            qDebug() << "After QSoundEffect::stop() (" << elapsedTimer.elapsed() << "ms)";

            mButton->setEnabled(false);
        }
    }

    void doneLoading() {
        mButton->setEnabled(true);
    }

    void animate() {
        if (mLabel->text().size() == 40) {
            mLabel->setText(QString());
        }
        mLabel->setText(mLabel->text() + ".");
    }

private:
    QSoundEffect mSound;
    QVBoxLayout *mLayout;
    QPushButton *mButton;
    QLabel *mLabel;
    QTimer mTimer;
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QMainWindow mainWindow;

    AudioPlayer *audioPlayer = new AudioPlayer(&mainWindow);
    mainWindow.setCentralWidget(audioPlayer);

    mainWindow.show();

    return a.exec();
}

#include "main.moc"

void QAudioOutputPrivate::close()
{
    if(deviceState == QAudio::StoppedState)
        return;

    deviceState = QAudio::StoppedState;
    errorState = QAudio::NoError;
    QElapsedTimer t;
    t.start();
    int delay = (buffer_size-bytesFree())*1000/(settings.sampleRate()
                  *settings.channelCount()*(settings.sampleSize()/8));
    waveOutReset(hWaveOut);
    Sleep(delay+10);
    qDebug() << t.elapsed() << delay;

    freeBlocks(waveBlocks);
    waveOutClose(hWaveOut);
    delete [] audioBuffer;
    audioBuffer = 0;
    buffer_size = 0;
}