programs running in back ground slowing down speed

My computer seems slow sometimes, how do I go about checking to see If I have programs running in the back ground and How do I know which ones I need? Bubba

 

Maybe it may not work but one way for windows users you can use ccleaner http://majorgeeks.com/download4191.html and once you download and open it up. On the left will say tools, click that then click start up. Then will be things that start up when your computer starts. And under the part named (enable).. if it has a "yes" then that item starts up. And I wouldnt suggest disabling anything you don't know what it is... So post here and maybe someone will help ya.