[Q] looking for rooted app to save battery with changing the clock on cpu.

I'm looking for a app that can change the clock of my cpu with a push of a button, so i can save battery like we used to have on Jelly Bean the "Power Saving mode" button.

I'm new to android 4.4.4 always used 4.1.2, recently i changed my ROM and can't find any app or configuration on android similar to what used to be.

Edit: i'm aware about SetCPU app, but its not free and as far i know it uses profiles and is not like a button that i can instantly push and change my clock.