The GS4 that I had for a short period of time was a real slug compared to my new 6S Plus. I sold the GS4 to a friend who is still using and complaining about it almost everyday. Yet she doesn't want to go back to the iPhone.My GS4 had 2GB of RAM and couldn't even keep two apps in it without reloading one of them. My 6S can keep a game, multiple tabs open in chrome, youtube, app store, and google maps in the RAM at the same time before reloading the youtube app when I reopened it.