[Galaxy Note 3 General] BarryH_GEG:
What is "lag?" I don't think there's an "official" definition. If someone asked me if I thought my N2 (unrooted, stock) "lags" I'd answer no pretty quickly. But does it occasionally slow down doing certain things, hang every once in a while, and stutter opening a window or in a transition? Of course it does. I have 113 apps installed on my N2 and that's not counting all of Google and Samsung's pre-installed apps. The speed, fluidity, and consistency of the N2's behavior, especially with what I do with it, never fails to impress me. I'd say those things I described occur probably 1-2% of the time and usually pretty predictably (specific app, specific sequence of events). When they do occur they may be noticeable but we're talking about a millisecond long event.

There are probably 1K developers who've touched the code and apps running on my device. The odds of them all (including Google, Samsung, and third-parties) creating absolutely perfect code that's going to run flawlessly on hundreds of different h/w platforms is slim to none. An excellent example is Google themselves borking aspects of 4.2 and 4.3. So there's always going to be "lag" (however it's defined) because the ecosystem on Android phones can never be perfect because of its variability.

There are people on XDA that are obsessed with "lag" and go to any lengths to eradicate and sign of it. They are usually the first to ridicule the OEM overlays and spend most of their time with their device benchmarking them, spinning the home pages reveling in the smoothness of their transitions, and pinch zooming just to bask in how "lag free" their device is. For those people I ask "when do you have time to do anything on/with your phone?" I'd guess I'd probably spend 5-10% of my time with my device navigating and 90-95% actually getting things done or in specific apps doing specific things. The N2, even with TW, Samsung's apps, Google's apps, and my apps make the 90-95% of the time I'm doing stuff enjoyable. Maybe if people that spend 90-95% of their time playing "lag hunter" actually used their devices to do something the lag wouldn't be as obvious.

Here's an example of imperfection in the real world. My car has a seven speed transmission that 95% of the time is amazingly smooth. There are times when I'm accelerating it doesn't downshift perfectly. And it's not every downshift, just at certain speeds when I'm in a certain gear. So do I: A) enjoy my amazingly smooth (95% of the time) seven speed transmission; or B) camp out in the dealer service department having them tear my car apart in the pursuit of perfection? Should I also swear I'll never buy a car from "X" again? And how do I know that brand "Y" doesn't have the same issue (or worse)?

So lag hunters everywhere do carry on your mission. But know that every time I see your posts I just think "what a shame, they never get to actually use and enjoy their devices." To some here their device is a science project. To quite a few, myself included, our devices are tools to get things done, entertain ourselves, and share stuff with others. The latter category doesn’t have as much time as the former to obsess about imperfection; we're too busy doing stuff.