Are there any Cydia tweaks that can limit the amount of apps that can run in the background at any1 time.

e.g. set a limit of 5 apps, so when the 6th app is launched the first app gets killed.

I really want this kind of tweak because I've had enough of going into the app switcher and killing apps when Im down to less then 30mb of free RAM and my iOS device starts to get sluggish.