hey guys. I think I solved the problem by myself. I think n9qt has something to do with this. Not on the tweak, but on how you installed it. I remember , I installed n9qt 9.5.9 first then after a month I installed theme changer then followed by OPPtimizer and I did'nt get any problem with that. Then when I saw the n9qt 9.7.8, I can't update it so I decided to uninstall it and remove the n9qt back up. Then installed the new version. Then that's the next thing that happened next, it really overheats

So I uninstall it again, but still the problem exist.

I reflash my phone. Installed theme changer then followed by n9qt 9.7.8 but still problem exist

I reflash again my phone. Installed again n9qt 9.7.8 FIRST. then followed by theme changer, and it works fine now! No heat and No lags at all. And by the way I am playing music nonstop for almost 24 hours and it never heats up before and more that half of the battery still remains. Just now that something strange happened.

So I conclude that n9qt can't be stable if the phone had installed with a theme changer MOD first.