Remember how you can tap things and do a little voodoo to enable developer options in Android 4.2? Most of us still won't need to enable any of these other than USB debugging, but folks who are developers have some serious tools at their disposal in there. That's why we're fine with them being hidden for more normal users. Out of sight, out of mind, and the folks who need them know where to look.
One of those folks is Romain Guy. He's an extraordinary photographer, but he's also an Android engineer at Google who focuses on graphics and animation. In short, he knows what he's doing. Turns out he's a fan of the new Falcon Twitter client, and likes it enough to notice that there might be a hiccup or two in the timeline scrolling. Software engineers are regular people for the most part, but in our imaginations they grab a cable and a laptop to investigate anything that gets them curious. This time, out imaginations are correct.
Have an excellent read of just how he uses the developer tools available to track down the issue, and see just what developers have to go through sometimes to pump out awesome Android applications. Chances are you'll only understand part of it, but that will be enough to have a better appreciation of what these guys do.