FULL PRODUCT VERSION :
java version "1.8.0_161"
Java(TM) SE Runtime Environment (build 1.8.0_161-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.161-b12, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.15063]

A DESCRIPTION OF THE PROBLEM :
Swing applications uses a lot of CPU after upgrading to 8u161/8u162

REGRESSION.  Last worked in version 8u152

ADDITIONAL REGRESSION INFORMATION: 
Broken in 8u161/8u162
OK in 8u151/8u152
OK in 9.0.4

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run application
Click in JTextField
Click in another application (like Outlook, Chrome or other)
Click in JTextField.
After a few tries, CPU spikes

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No CPU usage after switching between applications
ACTUAL -
17% cpu load on an 8 core machine
29% cpu load on an 4 core machine

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Test1{
	public static void main(String... args) {
		JFrame f = new JFrame("Test");
		JTabbedPane tp = new JTabbedPane();
		tp.addTab("tab 1", new JTextField(20));
		f.add(tp);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.pack();
		f.setLocationRelativeTo(null);
		f.setVisible(true);
	}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Clicking the tab in the JTabbedPane seems to stop CPU usage.
I have found no other workarounds.

SUPPORT :
YES