Its a neat little daemon which can set powersave, balanced or performance power profiles. It is also integrated with KDE. I don’t know if its that way on every device, but my laptop heavily profits from it - during powersave mode it substancially increases the battery life for example. Iirc it works by limiting CPU frequencies 
The issue with all kernels maintained by @ptr1337 is, that the patches used change their content and keep getting cached between builds, thus causing checksum mismatches. This time I manually corrected them, however I’ll need to look into a permanent solution for this again.