Share your experience!
Flash the phone with australian version of 4.3. That helped me. I will probably downgrade to 4.1.2 and wait for kitkat, bcs the screen keeps freezinga small bit every 1-2 seconds and ram usage is a bit higher, apps react slower.
I would like to help you both come over the hoax of 4.3-FEAR 
My SP is running butter smooth since the upgrade though a friend of mine was experiencing some RAM issues after updating.. What he did was, REFLASHED his phone via PCC and viola!
Yet his case was a total disaster after the first update.. . His phone wasn't even able to open the MENU for like 15 to 20 seconds.. .
You can still go for GREENify (free in the app store) which will let you add a shortcut icon on your homescreen allowing to disable RAM hungry apps which you would need to select..
I just added facebook, Skype and Viber in that list and my phone works for around 3 days without games (the buttery smooth thing comes into play all the way). And if I play games I still get around a day of charge 🙂
All you need to do is use Greenify to mass-disable all the apps and THEN play the heavy games