ListSelectionListener causes View to freeze - only if external LookAndFeel is activated

Question

I have quite a specific problem with Swing on OpenJDK 11 and im curious if someone have an idea to help with this. Im using Swing in my software and in one of my dialogs the program is freezing for a while every second or third click on a JTable. The changes caused by that are beeing processed in a ListSelectionListener starting like this:

 getSelectionModel()
    .addListSelectionListener(
        e -> {
          if (!e.getValueIsAdjusting()) {
          ...

This happens only when using OpenJDK 11. I'm also using an external LookAndFeel where i dont have access to the source code. If im disabling the LookAndFeel everything works fine as well - even with OpenJDK 11. But also the View works fine, if i comment a part of my code. The most interresting part is - wherever i do a system time output in the listener to find the problem there is no bigger delay. Even if i use my code which seems to be able to cause delay. The delay is always happening before. So my guess is that the LookAndFeel maybe overwrites some swing internals which struggles with processing the Events. Does anyone here has an idea which function or part of swing could cause that behaviour?

On Java 8 everything used to work fine. I'd appreciate every clue to solve that.