not a huge sample size but it’s only logical since the menu is always visible ;
- STICKY MENUS ARE 22% QUICKER TO NAVIGATE
- 100% PREFERRED STICKY MENUS WITHOUT KNOWING WHY
Facebook and Google+ recently adopted sticky navigation, but they are among the minority. Of the 25 most visited websites in the US, only 16% currently have sticky navigation. Below are some examples of other websites that do an excellent job of pulling this off.
- DESIGN LIMITATIONS
- DISTRACTING AND INTRUSIVE
- MOBILE COMPATIBILITY
Complete article, http://uxdesign.smashingmagazine.com/2012/09/11/sticky-menus-are-quicker-to-navigate/