I tried to keep a 0.5 delay when showing the popup, but this lead to another problem. When you are playing with the mouse and moving it over the contact list area, there were cases when the mouse was positioned to a contact, but the popup showed was of another contact.
In the original code, the 0.5 delay didn't work either. Because of the delay, the mouse motion listener didn't do anything first time mouse enters the contact list area (popup not shown). On the next mouse move, the popup started to be shown with no delay.