+1... the best task manager is Android OS. However, samsung seemed to feel the need to put an optimizer in the system settings. If you gotta do it, that is as "good" as anything else.
Android is different... Free RAM is WASTED RAM!!! You want your RAM FULLLLLLLL. There is absolutely no reason to have spare empty ram. You don't need to clean it out. In fact, cleaning your ram, actually SLOWS YOUR PHONE DOWN. There is a ton of ram in this device (since many cheaper phones still come with 2 GB, not the 4 GB we have. Apps are stored (NOT RUNNING) in the background ram space. When you want to go back to an app, you can press its icon or use the previous apps button, and POW its there, ready to go. When you clean your ram, you need to reload those apps from scratch. Significantly longer process. You are NOT saving battery by having the RAM cleaned, or closing all the items in your previous apps menu. They are there, just not doing anything.