How can i speed up the animation of hiding the menu bar?
As of macOS Sierra 10.12.6 there is no preference for controlling the animation speed of the menubar hiding animation. It used to be there, but was removed in Yosemite. The only workaround is to press Ctrl-Fn-F2 (or Ctrl-F2 if you inverted the Fn key) to immediately show and activate the menu bar. You can then navigate by keyboard or click items with the cursor.