Paint program lags when mouse dragged is moved fast

import javax.swing.*;


public class CanvasInitializer {
    public static void main(String [] args){
        CanvasPanel canvasPanel = new CanvasPanel();
        canvasPanel.setSize(500,500);
        canvasPanel.setTitle("Canvas");
        canvasPanel.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        canvasPanel.setVisible(true);
    }
}

import javax.swing.*;

import java.awt.*;
import java.awt.event.*;
import java.util.*;



public class CanvasPanel extends JFrame {
    private Brush brush;
    private LinkedList<Brush> brushList;
    private JButton clear, erase;
    private Map<String,Color> map ;
    private Canvas canvas;
    private JComboBox<String> jComboBox , brushCombo;
    private String [] brushTips = {"Small", "Medium","Large"};
    private Color [] colors = {Color.BLACK,Color.BLUE, Color.CYAN, Color.GRAY,Color.DARK_GRAY, Color.LIGHT_GRAY, Color.GREEN,
                                            Color.MAGENTA,Color.ORANGE, Color.PINK, Color.RED, Color.WHITE, Color.YELLOW};
    private String [] colorArray = {"Black","Blue","Cyan","Gray","DarkGray","LightGray",
                                   "Green","Magneta","Orange","Pink","Red","White","Yellow"};
    private Color colorSelected = Color.black;
    private int xGrid,yGrid, width, height;

    public CanvasPanel(){

        clear = new JButton("Clear");
        erase = new JButton("Erase");
        map = new HashMap<String, Color>();
        brushList = new LinkedList<Brush>();
        jComboBox = new JComboBox<String>(colorArray);
        brushCombo = new JComboBox<String>(brushTips);
        canvas = new Canvas();
        canvas.requestFocus();

        for(int i = 0; i< colorArray.length; ++i){
                map.put(colorArray[i], colors[i]);
        }

        JPanel topPanel = new JPanel();
        topPanel.add(jComboBox);
        topPanel.add(brushCombo);
        topPanel.add(clear);
        topPanel.add(erase);

        clear.addActionListener(new ButtonListener());
        erase.addActionListener(new ButtonListener());
        jComboBox.addActionListener(new ComboBox());
        brushCombo.addActionListener(new BrushTip());
        canvas.addMouseMotionListener(new PointListener());


        JSplitPane sp = new JSplitPane(JSplitPane.VERTICAL_SPLIT, topPanel, canvas);
        setLayout(new BorderLayout());
        add(sp);
    }




    public class Canvas extends JPanel implements Runnable{
           public Canvas(){
          setBackground(Color.WHITE);
        }
        protected void paintComponent(Graphics page){
            super.paintComponent(page);
            if(!brushList.isEmpty())
                for(int i =0; i< brushList.size(); ++i){
                    brushList.get(i).drawImage(page);
                }


        }

public class Brush {

     private int x, y, width, height;
     private Color color;

    public Brush(int x, int y,int width, int height, Color color){
     this.x = x;
     this.y = y;
     this.width = width;
     this.height = height;
     this.color = color;

    }

    protected void drawImage(Graphics graphics){
        graphics.setColor(color);
        graphics.fillOval(x,y,width,height);

    }

}