There seems to be a performance issue with the listbox in ZK 8.6.0. After migration from 8.5.0 IE11 is waiting about three minutes for a response, so I have to abort the JavaScript executing. With Chrome the listbox is loaded after 10 seconds. The listbox consists of about 50 elements.
The performance is getting better if I

• avoid images in the listcell
• avoid autopaging
• avoid apply tags within the listbox.
  Please check the attached file for more information.

After some profiling with Chrome developer tools I could find out that the cause has something to do with the JS function doSyncScroll.