*Note that this requires a jailibroken iPhone or iPod Touch for access to the Cydia app store
Sick of that lag in iOS4 on your iDevice? Losing 20% of your battery life overnight? Fire up Cydia and do a search for zToggle (Its free). Install it and run. Select your make of iDevice from the list and you’ll be presented with toggle switches to enable and disable multitasking and background wallpaper. Flip the switch and reboot. Voila! Welcome back to a faster OS with better battery life.
Tested on a iPod Touch 2G jailbroken using redsn0w with multitasking enabled.