Higher CPU = less battery time. Thats for starts.
Secondly, a mobile OS should be an OS which is developed to use as minimal resources as possible, so it'd not interfere with the applications running on it, and leave most of the resources for those applications for use.
If your OS is a resource hog, the solution is NOT to build a better platform with more resources hardware-wise, but to build your OS to be slim and smart to begin with.
Stronger hardware is not a solution for a bad code - fixing the code should be the solution.