More powerful computers, as well as the rising costs for energy require modern computing systems to be more and more energy efficient. A modern approach in order to solve this issue is the usage of multi-core processors instead of single-core processing units. This paper focuses on modern ARM multi-core processors, which combine powerful and energy efficient processor cores on a single chip, in order to reduce power consumption and increase performance. To verify how much energy can be saved and how much performance can be gained by using multithreaded software, we have simulated a various number of different calculation scenarios for a modern ARM System-on-Chip. The results of these simulations show notably, how advantageous the usage of multi-core processors and power saving processors together on a single chip is. By using intelligent multi-threading concepts, the processor is able to reduce its power consumption by up to 60% compared to a single-threaded execution.