Flashing Kernel may Void your warranty, but I will advice you to flash Gluon as it will give a new life to your Phone (Though I am not held responsible for any mistake you make during flashing it).
I used it on my stock rom for more than 6 months with amazing performance and battery backup.
First go to Settings>Developer options and enable USB Debugging
Go ahead follow the steps properly and flash it. (Root Needed) Don't know how? Check here
1. Install ClockworkMod 220.127.116.11. You'll find it here. http://forum.xda-developers.com/show....php?t=2669806
2. Copy Gluon Kernel zip into your extSDcard.
3. Reboot to recovery
4. Select Install zip from sdcard and find the Gluon Kernel Zip and install it.
5. Reboot and check the name of the Kernel in About section.