It is rightly said that you do not realize the true capabilities of the Android operating system until you have rooted it and used custom Rome to take advantage of the magnificent hardware profiles. Even though considered as a risky process as you may brick your device rooting is a must for every android user. After you have installed a custom kernel or ROM on your device you would want to over clock or under clock your device based on your needs. Previously we wrote a detailed article on Mobile phones overclocking.
To go about changing the speed of your processor the application safest is set CPU. It is a paid application for about $.99 but totally worth it. You can change the speed of your processor to suit your needs, increase the speed in case you want faster operations or reduce if you are running short of battery and need to conserve.
You also have the added options of creating a profile so satisfying your conditions the processor speed will be automatically set. For example if you want the maximum speed to not exceed beyond 800 MHz while you are below say 25% of your battery you can create a specific profile for that. You can also set priority of a certain profile in case there is a clash of profiles then what should be given a priority.
The UI is rather easy and straightforward. However it is highly recommended that if you are using this application for the first time or are absolutely new to rooting and such processes, do not attempt to do everything by yourself and seek expert guidance so that your device is safe and you do not do physical harm to the processor by over heating it and such.
Once you are in the know about set CPU is extremely easy to use and highly customizable option to set speeds of your processor.