How power management improves computer performance?

Answer 1

Performance means many different things. Power management is designed to find a good compromise between power consumption (with the aim of reducing power consumption) and computing performance (with the aim of providing sufficiently fast handling of calculations and events). Power management thus improves the computer's performance in terms of battery lifetime.

However, power management algorithms do not simply try to minimize the power consumption by slowing down a computer. Instead, power management algorithms generally try to find a good compromise based on the current demand. Thus, as demand grows, power management might increase the CPU speed, enable more CPU cores or take similar steps to enhance the computing performance (at the expense of increased power consumption).

As long as power management algorithms are allowed to find the best compromise automatically (as opposed to being forced into rigid "minimum power" or "maximum CPU performance" policies), power management algorithms will generally improve the overall computer performance thus.