https://blog.wongcw.com/2018/08/06/%e5%a6%82%e6%9e%9c%e4%bd%a0%e5%8e%9f%e5%85%88%e7%9a%84%e7%92%b0%e5%a2%83%e6%98%af-powersave-%e6%83%b3%e6%94%b9%e6%88%90-performance-%e6%99%82%ef%bc%8c%e6%80%8e%e9%ba%bc%e5%81%9a%e5%91%a2%ef%bc%9f/