In Android, processes and Applications are two different things. An app can stay running in the background without any processes eating up your phone’s resources. Android keeps the app in its memory so it launches more quickly and returns to its prior state. When your phone runs out of memory, Android will automatically start killing tasks on its own, starting with ones that you haven’t used in awhile. On Android, having your RAM nearly full is a good thing. So while Android actually uses RAM efficiently, most users see that their RAM is full and assume that’s what’s slowing down their phone.

Apps like Advanced Task Killer, the most popular task killer in the Market, act on the incorrect assumption that freeing up memory on an Android device is a good thing. When launched, it presents you with a list of “running” apps and the option to kill as many as you want. You can also hit the Menu button to access a more detailed “Services” view, that lists exactly which parts of each application are “running”, how much memory they take up, and how much free memory is available on your phone. This set-up implies that the goal of killing these apps is to free up memory. Nowhere on the list does it mention the number of CPU cycles each app is consuming, only the memory you’ll free by killing it. As we’ve learned, full memory is not a bad thing—we want to watch out for the CPU, the resource that actually slows down your phone and drains your battery life.
[via lifehacker]