Frasier Speirs, “Misconceptions About iOS Multitasking“:
There is one iOS “tip” that I keep hearing and it is wrong. Worse, I keep hearing it from supposedly authoritative sources. I have even heard it from the lips of Apple “Geniuses” in stores.
Here is the advice – and remember it is wrong:
All those apps in the multitasking bar on your iOS device are currently active and slowing it down, filling the device’s memory or using up your battery. To maximise performance and battery life, you should kill them all manually.
Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. Wrong.