Change the Animation Speed of Hiding & Displaying the Mac OS X Dock
Automatically hiding the Dock is one of the more useful features you can enable if you work on a Mac with limited screen space. That experience can be improved by removing the auto-hide delay from the Dock in OS X, which reduces the delay from when a mouse is hovered near the Dock to when it’s displayed, but now we’ll show you how to speed up or remove the slide-in and slide-out Dock hide and show animation itself.
Remove Dock Animation Completely
First up, removing the Dock animation completely, this makes an auto-hiding Dock snap into place immediately. Launch the Terminal and use the following defaults write command:
defaults write com.apple.dock autohide-time-modifier -int 0;killall Dock
The Dock will automatically restart with the changes taking effect.
Set an Ultra-Fast Dock Hide & Display Animation
This leaves the Docks animation intact, but speeds it up dramatically. You can adjust this yourself by changing the numbers after the -float flag:
defaults write com.apple.dock autohide-time-modifier -float 0.12;killall Dock
Restore Default Animation Speed
Return to the OS X default animation speeds with the following defaults write command:
defaults delete com.apple.dock autohide-time-modifier;killall Dock
Thanks to Levi for the tips in our comments!