Consider your device a mini computer, in order for it to do anything it’s reliant on its ability to process new information, write that information to memory, and then output that information to your screen. Like all computers, its ability to perform well is dependent on all of the components/factors working together as one unified system; starting from its core/foundation (hardware) ranging all the way to the user apps. Each layer plays an important role regarding how your device will perform, however the farther and farther you move away from the Hardware Level (level 1) regarding tweaks/mods/settings, the potential benefits will decline in their relative significance. Therefore the best way for me to explain what it will take to improve the overall performance of your device, will be for me to methodically and sequentially break down the specifics regarding each of these levels:
Level 1_ Hardware & External Factors
Level 2a Kernel
Level 2b Operating System
Level 2c Base/Framework (ROM)
Level 3_ Applications
When it comes to optimizing battery life and speed, if you can learn to tackle it from all three levels, you will achieve the gains you are after. Furthermore, becoming a root user will give you ability to do all the things discussed in this thread. As a non root user you are very limited as to what you can accomplished regarding system optimization; the only things you can do as a stock ROM non rooted user, is to buy an extended battery, lower your display brightness (you can’t even use the app adj brightness), reduce the frequency your apps fetch data, and use an app like juice defender; those literally are your only good options, everything else discussed in this thread requires you to be a root user, why? – because the primary battery saving techniques on the system level, require you to have system level access, and unfortunately for you non root users, you don’t have this type of access. If you are interested in rooting, check out my post here on the reasons why you should and how you can go about doing it. Enjoy!