That's definitely a bug. It's instant for me.

But I do think some of the systray things are overly complicated. E.g. why does the volume widget list all audio outputs and inputs by default?

On the other hand some things are really great. E.g. which other DE lets you adjust the screen brightness (the real one via DDC/CI) from the systray, or start video screen capture by pressing print screen?

KDE is definitely better than gnome at this point.