We all know the more apps is indeed the better, as long as they are useful and can improve our device's performance. But at the same time could give you trouble if all the opened apps running on the background while you don't use them.
Yes they are running in background albeit not being used, as the result your iPhone, iPod Touch or iPad's CPU and RAM are eaten by them and would certainly slowdown your device performance.
Apple since the iOS 7 gives the whole new experience of multitasking tasks compared the previous versions like iOS 6 and lower.
To close the apps we can double press the Home button to firstly minimize them and then close it one by one. Surely it's time consuming task.
How To Close All Running Apps In iPhone Background
And this is very useful to avoid us from being one-by-one closing the running apps in iOS 7 based iPhone, iPod Touch or iPad.
However to utilizing the Slide2Kill tweak from Cydia then you need to have a jailbroken iPhone, iPod Touch or iPad. You can untethered iOS 7 using Evasi0n iOS 7 jailbreak tool.