Speed up Your Mac’s Window Resizing Animation With Terminal Command
When you resize a window in OS X, a nice little animation appears showing the window expanding. If you don’t like this animation (or it’s just choppy and slow on your old Mac), OS X Daily shows you how to turn it off and resize instantly.
All you have to do is open Terminal (Applications> Utilities) and then type:
defaults write -g NSWindowResizeTime -float 0.003
Then restart all running applications and from now on, the resize will be instant. Keep in mind that if you are in Yosemite, you can revert the resize behavior by Option-clicking .
Make Instant Resize Window Animation Speed On Mac OS X | OS X Daily