What Makes Software Energy-Efficient?: Make it Faster

In order to reduce software energy consumption, a lot of studies have been carried out focusing on the difference of implementation, such as API and algorithm. However, we hypothesize that there is a strong correlation between total energy consumption of a program and duration of its execution. If this hypothesis is correct, reducing energy consumption is equal to decreasing duration. Experimental results reveal that there is a strong positive correlation between them, and its correlation coefficient is higher than 0.9. We also find that memory usage is weakly correlated with total energy consumption. As a result, we conclude that if developers want to reduce software energy consumption, they should firstly decrease duration of execution, and secondly reduce memory usage.