Thanks to author and programmer Mike Ash for this developer-focused explanation of Apple’s move to the 64-bit A7 chip in the iPhone 5s. In short, although details will vary by app, 64-bit code that takes advantage of new programming techniques can be faster and use less memory (though 64-bit apps use more memory in general). Plus, old 32-bit code can run on the A7 with no changes or performance penalty.follow link
Option-click to Hide Apps Quickly
This trick has been available in the Mac OS for years, but many people still don't know it. If you have too many windows cluttering up your screen, you can hide specific ones easily as you work. When you're in any application, hold down the Option key and click on another app's window, on the Dock, or in the Finder to switch to that other app and simultaneously hide all the windows in the previously current app.
- ExtraBITS for 07 October 2013 (07 Oct 13)
What 64-bit Support in iPhone 5s Really Means