Javax.swing.SwingUtilities.invokeLater make my program slow

Question

i am writing a program in which i am implementing documentlistener
to communicating between two frames
if i write my code with javax.swing.SwingUtilities.invokeLater it makes my program slow
and if i write without this thread safe quality then this is fast but giving me runtime exception
what i do to make my program better
kindly suggest
public void insertUpdate(DocumentEvent e) {
            updateLog(e, "inserted into");
        public void removeUpdate(DocumentEvent e) {
            updateLog(e, "removed from");
        public void changedUpdate(DocumentEvent e) {
            //Plain text components don't fire these events.
        public void updateLog(DocumentEvent e, String action) {
            Document doc = (Document)e.getDocument();
javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
tf4.setText(lbl.getText());
}

Answer 1

If your program is becoming too slow or unresponsive, it means that the operation "tf4.setText(lbl.getText());" is taking too long to execute and is therefore blocking the Swing-thread.
There is little you can do to make that operation faster, but perhaps you can change how or how often you update the frames.
Setting the whole text via setText() everytime a change happens seems very wasteful. Imagine you have a text with a million characters, and every time the user adds or changes just one character, you are getting and seting over one million characters. That is not the right approach.
I'm not familiar with text-operations or class DocumentEvent, but I guess that there should be some kind of delta in DocumentEvent containing only the changes that were made. You could apply only these changes on tf4 instead of setting the whole text. Finding out how to do this would be the best solution. This will also make your program more scalable, as with setText() the performance of your application will continuously decrease as the text length increases.
Usually when working with documents you have a "viewer" and a "model". If your viewer was a JTextBox and your model was, say a StringBuilder, you could make quick changes to the contents of JTextBox using the StringBuilder.append() or delete() methods without having to modify the whole text. You need to find out how this is done with whatever UI system you're using.
If you can't find out how to do the above, a workaround would be to reduce how often you call "updateLog()". For example, is it truly necessary to call "updateLog" every time a new update happens? Perhaps it would be better to use a timer and only call "updateLog()" every few seconds.
But as I said, this should only be a temporary workaround. You really should find out how to perform more efficient updates without using setText(). I recommend you search for tutorials and guides on how to work with text and documents on the internet.