I'm not here asking for support in anything but to share a solution that helped me!
My Galaxy SIII was working very well especially after the 'fixed' 4.3 update. I study in Egypt and my parents work in Saudi Arabia so in the last mid year vacation I went there for 25 days. It suddenly stopped working as normal and kept freezing for very long time and very frequently. I know about the Galaxy SIII Sudden death syndrome and I found that my chip was 'insane'. I did think that was the problem. Before going to Samsung I installed Cyanogenmod and it worked like charm and I also used a software called 'Dummy file generator' and created MANY dummy files in internal memory because I red that the Samsung prevented the SDS in 4.1.2 update and above but the fix caused lags that were fixed by creating dummy files. I study medicine and I didn't understand that well LOL.
When I returned back to stock the problem came again!
The problem was that I joined our Wifi network in KSA using wireless push button which starts a hardware bug on the device... but because CM doesn't have an option for using the wireless push button it had no problems.
So my conclusion was:
If your SIII has constant frequent long lags, mostly it is not because of the insane chip because Samsung already patched that!
Dummy file generator worked for many but worked temporary for me and I don't think it fixes a root cause.
There is a bug that causes feeezing when you join Wifi network via the push button, so type your password and see if your Galaxy SIII works normal again before searching for other solutions or going to Samsung.
DON'T USE WIRELESS PUSH BUTTON ON GALAXY SIII!!
Thanks for reading