If you own a Smartphone, you probably have a task killer application installed. The ubiquity of these applications springs from the belief that they magically increase battery life, allowing the Smartphone to last for a few more hours on a given day. However, that is not true.
On testing these task killer applications on five different 4G Android phones, a PC World report concluded that there was no substantial increase in battery life (with HTC Evo 3D running about 15 minutes more). On some phones, the battery life decreased. The decrease wasn’t substantial either — but the data is enough to conclude that task killers don’t make a significant difference in prolonging the battery life of a smart phone.
Here’s why: On Android phones, many applications automatically restart themselves even after you nuke them with a task killer (this is why you see your phone functioning faster for a while, only slowing down later).
Other applications that remain in memory (RAM) don’t actually eat up your CPU resources. Because they stay in memory, they only use lesser CPU cycles when relaunched. But by killing them instead, one only causes the CPU usage to increase because they have to start all over again. You should use only a task killer application when a badly coded application runs wild.
Killing tasks on the iPhone is even worse. When you double press the Home button on your iPhone, what you see is a multitasking bar or the app switcher – and it only shows you a list of recently launched apps in order. These applications aren’t running in the background — iOS automatically suspends applications a short while after you press the Home button, and killing these applications is not going to make a difference at all. The next time you tap that task killer widget on your home screen: think twice. Better yet, get rid of the task killer app itself.