Galaxy S3 high RAM consumption even on idle

Question

I have a Galaxy S3 International Version, without any modification whatsoever-- no rooting, no nothing. It is as good as a stock phone with a few Play Store apps.
However, of late, I have begun experiencing problems

I do not have background processes (of my own) running and even then all I have left free in the RAM is usually only 300MB of the 800MB that is there. Task killers cannot free more than that.

I experience lag when opening settings. What I mean is this: Say I click on the Battery option under Settings. There is a visible lag between the time I press the option and when the battery information is actually displayed on the screen.

Android Version: 4.1.2
Build Number: JZO54K.I9300XXEMF6

Answer 1

First a few things on the symptoms:

• On Unix/Linux/Android, "free RAM" is considered a "wasted resource". If RAM is not occupied by running processes themselves, the system uses it to buffer and cache other things, like the file system. This should speed things up, as usually RAM allows faster access.
  For more details, please check out ram tag-wiki.
• "task killers" are discussed controversely. While most (if not all) people agree they are fine to stop "rogue processes", it's certainly not their job to "free up RAM" or even "save battery". In these terms, they are rather contra-productive, as most killed processes simply restart themselves (which costs more battery than if they'd kept running, and fills up the "freed RAM" again as well).
  For details on this, closer information can be found in the answers on e.g. Do I really need to install a task manager?, Do task killers actually work? and Is it advisable to run a task killer app on Android.

And finally, to the issue itself (experiencing lags). As you describe it as a problem "growing with the time" (i.e. it was not there in the beginning, but slowly became more and more visible), you will probably find some help in the answers to My device is getting slow, apps start misbehaving/crashing. What can I do?

Answer 2

The lag you're seeing is unrelated to RAM usage. My "international" S3 runs the stock ROM and isn't rooted. Right now it has 277 MB free and it never lags at all.

As Izzy explains, free RAM is not a predictor of performance on Android. Android tries its best not to remove processes from RAM when they stop running, because if the same process needs to run again, it would cost energy and cause lag to load it into RAM again next time.

The only time you get lag as a result of RAM use is after you've used one particular RAM-hungry app. When one app hogs all the RAM, all these "cached" processes get evicted from RAM to free it up. Then, when you switch to a different app (even the launcher or settings), Android has to stop the memory-hungry process and load the new one into RAM from storage.

Oddly enough, this is the behaviour you get for every app, if you use a task killer to keep stopping background or cached processes, or if you force-close every app (or swipe them out of the recent apps list).

Answer 3

Very elegant solution - root the phone, download nobloat app. Disable all unnecesary processes - google for the ones u can disable . My phone is 500% more responsive after this. I am using original samsung 4.3 rom .