It's because of the flyout menus. When you're in it and move to the second level, you often take the shortest path, leaving the navigation panels. I can reduce it a bit, but a sub-one-second setting was too strict when I tried that.

It still seems a bit slow. A delayed reaction. I don't suppose this is something one can change via CSS or something like that. I never had an issue with the faster speed before these changes. Maybe I'm alone in that...

It seems to be inconsistent, however. In my test album, moving between the F1 and F3 menus is very fluid. But moving between either of them and F2 produces a long delay.

https://jefftucker.jalbum.net/pbMenu/

ETA: Some little timing anomalies, too. If I go back and forth between F1 and F3 a few times, F1 sometimes stops responding to a mouseover, and it has to be clicked to expand, or you have to move to one of the others, then back to F1 again.

Mouseovers have always been tricky - they sometime behave differently in different browsers, so coding for them is a high wire act.