Problem: Slow drawing on a jpanel

Hi everyone! I am working on a free draw project but I've been stuck. I am trying to create a XPanelGraphics (extended JPanel) in which I can draw. The user can either draw or erase what he/she has drawn. I use jLayeredPanel with two layers, xPanelGraphics both. Here is the code of the XPanelGraphics

public class XPanelGraphics extends JPanel implements MouseMotionListener, MouseListener {

public XPanelGraphics(){
        super();
        initComponents();
    }

private void initComponents(){
        this.addMouseListener(this);
        this.addMouseMotionListener(this);

drawingEnabled = true;
        penColor = Color.red;
        stroke = new BasicStroke(10f, BasicStroke.CAP_ROUND,
                                       BasicStroke.JOIN_ROUND);

initImage();

}

/*
     * Paint Methods
     * 1. initImage() = Initialization of the image area
     * 2. clearImage() = Turns the color of image area to background color.
     * 3. draw(...) = The user draws
     * 4. eraser(...) = The user erases
     * 5. paintComponent(...)
     */
    private void initImage(){
        int w = 2000;//getWidth();
        int h = 2000;//getHeight();
        drawingImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
    }

public void clearImage(){
        Graphics2D g2 = (Graphics2D)drawingImage.getGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);

//Enable transparency
        g2.setComposite(java.awt.AlphaComposite.Clear);

g2.fillRect(0, 0, drawingImage.getWidth(), drawingImage.getHeight());

//reset alpha composite
        g2.setComposite(java.awt.AlphaComposite.SrcOver);
        g2.dispose();
        this.repaint();
    }

public void draw(Point start, Point end){
        penJP.setLocation(start);
        g2 = drawingImage.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setPaint(penColor);
        g2.setStroke(new BasicStroke(penJP.getWidth(),
                                     BasicStroke.CAP_ROUND,
                                     BasicStroke.JOIN_ROUND));

g2.draw(new Line2D.Double((start.getX() + penJP.getWidth()/2),
                                  (start.getY() + penJP.getHeight()/2),
                                  (end.getX() + penJP.getWidth()/2),
                                  (end.getY() + penJP.getHeight()/2)));

g2.dispose();
        repaint();
    }

public void erase(Point start, Point end){
        eraserJP.setLocation(start);
        Graphics2D g2 = (Graphics2D)drawingImage.getGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);

//g2.setPaint(this.getBackground());
        //Enable transparency
        g2.setComposite(java.awt.AlphaComposite.Clear);
        g2.setStroke(new BasicStroke(eraserJP.getWidth(),
                                     BasicStroke.CAP_ROUND,
                                     BasicStroke.JOIN_ROUND));
        g2.draw(new Line2D.Double((start.getX() + eraserJP.getWidth()/2),
                                  (start.getY() + eraserJP.getHeight()/2),
                                  (end.getX() + eraserJP.getWidth()/2),
                                  (end.getY() + eraserJP.getHeight()/2)));

//reset alpha composite
        g2.setComposite(java.awt.AlphaComposite.SrcOver);
        g2.dispose();
        repaint();
    }

@Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        if(drawingImage == null)
            initImage();
        g.drawImage(drawingImage, 0, 0, this);
    }

@Override
    public void mouseDragged(MouseEvent e) {
            Point p = e.getPoint();
            if (drawingEnabled)
                draw(start, p);
            else
                this.erase(start, p);

start = p;
    }

@Override
    public void mouseMoved(MouseEvent e) { }

@Override
    public void mouseClicked(MouseEvent e) { }

@Override
    public void mousePressed(MouseEvent e) { start = e.getPoint(); }

@Override
    public void mouseReleased(MouseEvent e) { }

@Override
    public void mouseEntered(MouseEvent e) { }

@Override
    public void mouseExited(MouseEvent e){ }

private java.awt.Point start;
    private java.awt.image.BufferedImage drawingImage;
    private java.awt.Color penColor;
    private BasicStroke stroke;
    private boolean drawingEnabled;
    private JPanel eraserJP;
    private JPanel penJP;

}

The problem is that it is really slow. For example when I am trying to draw a circle quickly, the result I get is what you see in the attached png file. Is there a way to make it faster?