|The technology in use delivers enough CPU cycles to perform the task at hand. That assumes the unit is performing as designed.|
Running a laptop at full processor speed all the time will probably overheat the computer.
Running the processor faster will require a cooling fan to run. The processor itself would use more electricity and the fan would add to the electrical use. Those items combine to add up to shortened battery life.
An analogy would be an automobile. You can have a car with a 200HP engine. The only time you might need all that horsepower would be to drive wide open. However, you only drive 70MPH on the freeway, which may require 80HP. That is all the engine will produce.