If there's anything that will kill your laptop's battery quickly, it's running background apps. They'll often chew up a lot of processor power regardless of what they're doing. Microsoft wants to do something about that on Windows PCs. It just released an Insider preview build of Windows 10 whose Power Throttling feature should keep the amount of CPU work to a minimum. If you have a portable PC with at least a 6th-generation Intel Core processor inside (wider support is coming), Windows can switch the chip to a more energy-efficient state when background apps are active. Those background apps will still get their work done -- they just won't be as demanding as they would be if they were front and center.