Well not to start off too blunt but “NO” Task Killers on your Android Device do little to nothing to improve your phones performance. Almost every user of an Android Device that I know either has or has used a task killer for clearing memory on their phone. There are even others that have had their carriers install task killers before they leave the store with the promise of increasing battery life. Android like any other operating system will take care of these “running applications” for you.
One of the great things about Android is the ability to run multiple apps at one time. Some of these apps are in the background while you are using something else. While its true that these apps that are “running” are taking up memory they aren’t actually running as you would think. The apps in the background are actually paused until you come back to them. What this means for you is the apps are taking up space in memory but not actually doing anything to eat battery life.
Lets take a look at an example where you would like so many others worry about running out of memory. You open up an app and play your favorite game. Then you decide you want to get onto the internet and look something up. When you leave the app it pauses. No resources are being used by this app besides memory space at this point. So after getting on the internet you find some great videos and forget about your game. Later on in the day you have opened 50 other things and closed them and you have no memory left at this point. What android will do is now remove this game or other app you had running from memory to make room for the newest one you want to run.
Just keep in mind that Android is smarter than you think and is designed to function in a way that it doesn’t need you or a task killer to figure out what to close to free up room. Also there is no need to even think about battery when discussing whats in memory because it doesn’t effect the battery at all.
Don’t you think at this point if a Task Killer was that important that the Android OS would just include it?