If they're actually running, yes - they're using CPU and battery. If they're just still in RAM, but not running, there's no need. If Android needs the RAM space, it'll kill an app that isn't running to get it.
I never pay any attention to what's running or not. Android handles running processes quite efficiently. Odds are very good that if something is running, it should be running. Manually closing apps is contrary to how Android is designed to be used and can actually reduce performance. Please, see this for more details about why closing apps is poor practice:
You may - rarely - find a poorly coded app has failed to terminate or cache to memory properly and has 'gone rogue'. In such a case manual termination may be necessary but that's unusual.
I only close all running tasks when the "recents" list becomes too cluttered to navigate. In that case I'm looking for convenience more than being worried about resources.
That's actually not a good idea, for the same reasons. The Recent list maxes out at 50 and unfortunately that cannot be changed.. If that's too many, just go through as many as you want - 10, 20, whatever. No one is making you go through all 50. Just deal with as many as you want and ignore the rest. But don't close everything just just to keep the Recent cards short.
Now, don't get me wrong. Swiping away an app in Recent is not a Terrible Thing. That's not what I'm saying. I do it now and then myself and it's basically harmless. But doing it every time or closing apps wholesale is ultimately counterproductive.
I killed the TouchWiz app on my Samsung Galaxy S6 4G and it ruined my phone! After being sent for repairs in Sydney, Vodafone decided it was beyond repair, and so today I got a brand new S6 phone. ☺
I killed the TouchWiz app on my Samsung Galaxy S6 4G and it ruined my phone! After being sent for repairs in Sydney, Vodafone decided it was beyond repair, and so today I got a brand new S6 phone. ☺
What!! Really? The touchwiz supposed to restart again when you force close it. Or did you tried to uninstall it with root? Thats scary if just by closing touchwiz it bricked your phone.