How can I speed up dismissal animation of OS X notification dialog boxes? When I click to dismiss a notification dialog box in OS X Yosemite, it doesn't disappear immediately: it makes a kind of puff-of-smoke animation before it disappears. When you have more than one notification on the screen and click to dismiss the first one, not only does OS X do the puff-of-smoke animation but it also does a sliding animation to move the next notification box up to the top of the list. All of this takes time, which is not only annoying, but a real waste of time when you have to dismiss many notifications on the screen.

Is there a way to shorten the duration of those animations, or better yet, dismiss all visible notifications in one step?
You can dismiss all visible notifications by opening Notification Center and clearing notifications using the X at the top-right of the notification list.

Obviously this will remove all notifications for that particular date, so if you have others you want to save, this won't work. This is, however, the only way I am aware of to dismiss notifications en masse.

I'm also not aware of any way to remove the animations you mentioned.