Stop JScrollPane from high amount of redraws when scrolling

I have long text in Text Area placed to the Scroll Pane. I've noticed that when I rotate the mouse wheel, the text is redrawn severely, maybe even entirely.

This is the demo app:

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class TextArea {
  public static void main(String[] args) {
    final JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    final JTextArea textArea = new JTextArea();
    textArea.setColumns(80);
    textArea.setRows(20);
    textArea.setLineWrap(true);
    final JScrollPane scrollPane = new JScrollPane(textArea);
    textArea.append("1234567890 ".repeat(20000));  // Java 11
    frame.add(scrollPane);
    frame.pack();
    frame.setVisible(true);
  }
}

Redrawing can be easily detected if you place a logging breakpoint to the sun.java2d.SunGraphics2D.drawString(String, float, float) method. For me, it logs a couple of thousands hits when I rotate mouse wheel by a single unit (the number of hits depends on the size of frame). If I stop at breakpoint, I see that y position of the string to draw differs a lot and the difference is much more than the height of my screen.

I think it should better redraw only visible lines, or maybe even newly appeared lines.

Can JScrollPane be set up somehow to optimize the amount of draw calls? Or is it an unoptimized thing in Swing?

When I run this code and spin the mouse scroll wheel, the GUI doesn't flicker or change at all. The only reason I see my scroll wheel doing something is the JScrollPane tab moves upward.

I compiled to the Java 8 standard, using Java 14.0.2. My computer runs on Windows 10.

Not surprising, since the text is identical.

Try this complete runnable code and see if it makes a difference.

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class LargeTextArea implements Runnable {
	public static void main(String[] args) {
		SwingUtilities.invokeLater(new LargeTextArea());
	}

	@Override
	public void run() {
		final JFrame frame = new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		final JTextArea textArea = new JTextArea();
		textArea.setColumns(80);
		textArea.setRows(20);
		textArea.setLineWrap(true);
		textArea.append("1234567890 ".repeat(20000)); // Java 11
		
		final JScrollPane scrollPane = new JScrollPane(textArea);
		frame.add(scrollPane);
		
		frame.pack();
		frame.setLocationByPlatform(true);
		frame.setVisible(true);
	}
}

JTextArea indeed generates too much draw calls for a long line, seems like it redraws it fully and because of soft wrapping, it's split.

However, going deeper, it's visible that while scrolling, clipping area is set quite restrictively (to the newly visible space), so Graphics2D is able to skip drawing of all the strings that are outside of clipping.

So there is no need to worry because actually not much drawing should be performed.