[Xoom Android Development] kcrudup:
Lookin' for lag in all the wrong places

Guys- you CANNOT test for "lag issues" soon after (re-)booting when switching builds!

Whenever we make changes large enough to require Dalvik to reconfigure itself ("Android is Upgrading (Apps) ...") and/or changes to certain internal databases, there's going to be apps running for a while (as long as an hour on my Xoom, for example, 'cause I have ~40GB of movies, images and music the Media Scanner has to run thru) and they WILL eat CPU and run all over the flash disk, and these two reasons (the last especially) are 90% of why you get lag in Android. Open up any system monitor (I like System Tuner Pro" and "OS Monitor") and if that system monitor's not the top CPU user running, wait a while and then do your "tests" after that.

Aiso, "flicking launcher icons" is essentially meaningless as a test of lag, as the launcher itself is a large program in itself with a lot of data that has to be brought in, which means that if it's been killed off (or paged out, now that we're using a little bit of ZRAM swap) all that has to be brought back into memory, and "Launcher Lag" is one of those "luck of the draw" things that may or may not happen depending on what's been running, and what's in memory, and how much disk is being used, but LASTLY (and leastly) system CPU load. The Android system (and Android apps) are getting bigger memory footprints as functionality gets added over time, and what this means is that background apps (like the Launcher) have a greater chance of being pushed out to make more room in memory for something else (and if you're using a "Task Killer" app, STOP- you are not helping things out). The keyboard, what with the predictive typing and the amount of Framework usage that goes into it, is also a large app- and if it wasn't in memory, has to come back into it, so yeah, maybe your first few characters lag (and if you're typing into a webpage that's got Javascript running with every character, as I understand some versions of the XDA skin do, all bets are off- that ain't our fault).

This is not an iPad- Android doesn't limit the icon metadata nor lock in a simple launcher into memory just so people with "icon-swipe" fetishes can feel good about it- it's just not designed that way. The real test is "How fast do your favorite apps run?"

Lastly, and I'd posted this in the LTE thread, I think you guys with lag issues should turn on the CPU usage meter at all times. We've modified it so that it just gives a snapshot of both CPU and disk I/O usage. Go to Settings->Developer Options->Show CPU Usage and turn that on. You'll start to see a colored bar in your top right-hand corner; if you see more than a miliimeter of "blue" or "red", or if the first number is greater than about ~4.0, that means the system is tied up either in waits on the EMMC (flash disk) or in kernel processing, respectively, and the longer those are, the laggier the Xoom will be- and there's not much else we can do about it (and believe you me, I've put hundreds of hours into getting it to where we are now), mostly 'cause of the flash-disk part they chose when they built our Xoom.

Doesn't anyone think it's curious that half the folks here post how slow the SAME build that the other half thinks is OK? It's because of factors like this- the only thing really different on one Xoom vs. another running our builds is the apps people are running on it and the data they've got stored on it.

(TL;DR: if you're seeing lag, come back in an hour. Switching willy-nilly between builds otherwise doesn't help either you, or us in determining if there's a real problem.)