Steps to reproduce:

Run the code:
----------------------- 
import javax.swing.*;

public class JMenuTest {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            try {
                UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            } catch (Exception ex) {
                throw new RuntimeException(ex);
            }
            JFrame frame = new JFrame();
            frame.setSize(200, 200);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            JMenuBar menuBar = new JMenuBar();
            menuBar.add(new JMenu("Test 1"));
            menuBar.add(new JMenu("Test 2"));
            frame.setJMenuBar(menuBar);
            frame.setVisible(true);
        });
    }
}
----------------------- 

Compare the menu text with the sample which is run with the Metal L&F.
The text with the Windows L&F is twice bigger than the text with the Metal L&F.