When initially hovering upon a tab, the popup delay is just nice.
However, if you hover on the tab just beside it, you need to wait as long as the first instance.
So, if you want to hover over 10 tabs. It will take 10 times the initial popup delay!
Frequently in other programs, successive popup delay is set to zero. Because the user is already in "hover tooltip mode", it is assumed that he might want to see other tabs quickly in tooltip mode.
Once the mouse is away from the tree bar OR if an operation is performed on any of the tabs, this "quick hover mode" is reset. So the user has to wait for the "initial popup delay" again.
Customer support service by UserEcho