FULL PRODUCT VERSION :
java version "1.8.0_25"
Java(TM) SE Runtime Environment (build 1.8.0_25-b17)

FULL OS VERSION :
Microsoft Windows [S��r��m 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
multiple setEnable() method calls cause poor GUI performance and visibly slowness. But Actual problem caused by updateCursorImmediately() method call. If the component count is huge at a container In Java 1.6.0_45 method call result in under 1 second but in Java 1.8.0_25 It result in nearly 6 second.  Users are unsatistied by this situation. And We have couldn't migrate from 1.6 to 1.8.

THE PROBLEM WAS REPRODUCIBLE WITH -Xint FLAG: Did not try

THE PROBLEM WAS REPRODUCIBLE WITH -server FLAG: Did not try

REGRESSION.  Last worked in version 6u45

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
You can use the sample code the reproduce the performance problem

EXPECTED VERSUS ACTUAL BEHAVIOR :
Expected Result is that process of Disabling 1000 JButton is under 1 second.
Actual Result  is that It's lasting 6 second. 
ERROR MESSAGES/STACK TRACES THAT OCCUR :
There is no error message.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;

public class TestGUI extends JFrame implements ActionListener {

    private static final long serialVersionUID = 1L;

    public TestGUI() {
        initGUI();
    }

    public void actionPerformed(ActionEvent e) {
        String text;
        if(e.getActionCommand().equals("Enable-ALL")){
            enableAll();
            text= "Disable-ALL";
        }
        else{
            disableAll();
            text= "Enable-ALL";
        }
        ((JButton)e.getSource()).setText(text);
        ((JButton)e.getSource()).setEnabled(true);

    }


    private  void initGUI() {
        long m = System.currentTimeMillis();
        System.out.println("Initializing GUI");
        setTitle(System.getProperty("java.vendor") + " " + System.getProperty("java.version"));
        setLayout(new FlowLayout());

        JButton b = new JButton("Disable-ALL ");
        b.addActionListener(this);
        add(b);

        for (int i = 1; i < 10001; i++) {
            b = new JButton("Button " + i);
            add(b);
        }
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(600, 600);
        setVisible(true);
        m = System.currentTimeMillis() - m;
        System.out.println("GUI initialized in " + m + " ms");
    }

    private void disableAll() {
        long m = System.currentTimeMillis();
        System.out.println("Disabling");
        for (Component c : getContentPane().getComponents()) {
            c.setEnabled(false);
        }

        m = System.currentTimeMillis() - m;
        System.out.println("Disabled in " + m + " ms");
    }

    private void enableAll() {
        long m = System.currentTimeMillis();
        System.out.println("Enabling");
        for (Component c : getContentPane().getComponents()) {
            c.setEnabled(true);
            invalidate();
        }
        m = System.currentTimeMillis() - m;
        System.out.println("Enabled in " + m + " ms");
    }

    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable() {
            public void run() {
                System.out.println(System.getProperty("java.vendor") + " "
                        + System.getProperty("java.version"));
                new TestGUI();
            }
        });
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
I have no workaround.