Apple’s latest addition to Xcode, the Processor Trace instrument, is one of those features that sounds pretty mundane until you actually try it. Then you realize it’s exactly what you’ve been needing for the performance mysteries that eat up hours upon hours of your development time. If you’ve been developing apps for a while, this story will sound very familiar. Your app runs fine in testing, but then users complain about performance issues or excessive battery drain. You fire up Instruments, p...