Disable and re-enable animations Terminal commands I used the following Terminal commands to disable animations:

# opening and closing Quick Look windows 
defaults write -g QLPanelAnimationDuration -float 0

# showing a toolbar or menu bar in full screen
defaults write -g NSToolbarFullScreenAnimationDuration -float 0


from here:
How to turn off all animations on OS X

Are there Terminal commands to re enable them, just in case?

Also, that link suggested TinkerTool, but which option in TinkerTool is for disabling the Quick Look animation?
Try the following to re-enable them:

defaults delete -g QLPanelAnimationDuration
defaults delete -g NSToolbarFullScreenAnimationDuration


Those commands will delete the settings changes that you made, and OS X will reset them to the default settings.

Source: Wikipedia