Whether an app is running, in the foreground or background, it's using the battery. Kind of obvious. And what defines a 'battery hog' and how would anyone know if biteSMS uses more battery than stock? Does biteSMS run in the background? If you found out it does, would you stop using it? It's no different than telling the native Mail app to check for mail every x minutes. Something has to be running to do this check. Same for lock screen info, a weather app that shows the current temp in a bubble, etc. biteSMS uses Activator, as do a number of apps. My guess is Activator is running all the time in order to be able to intercept screen activity and take the appropriate action, if any.