My IPhone 4S keeps freezing - 1

So I've had my 4s for over a year now. It recently started having this issue were it will work perfectly fine. And a couple of minutes later I will open it up by pressing the home or power button and the screen will be extremely dim to where you can barely see anything and the screen doesn't touch at all! It will do the slide to unlock glow thing 5 or 6 times then freezes in the middle and the screen shuts off from the top like someone scrolled the screen down to the bottom. It will stay off for a couple of minutes them eventually turn back on or I have to. Sometimes when ill just leave it alone it will do the same thing. Yes I've restored it twice. I've been closing all my apps I've deleted some apps as well so I have 4 gigs or storage left. I have had no liquid damage to the phone as I know of. Please help! It does this when it charges as well!

Added (1). I also do not have any insurance what so ever for my phone

Should have got a windows phone

My phone did that too for a while, I went into the apple store and they said the software was messed up for some reason. They where very helpful and replaced my phone for free! I didn't lose any memory either!

Common things that slow your phone down can be:
Being in hot conditions
Having too many apps open on multitasking (double clicking the home button to display this)
Have to many windows open in safari (this takes up a considerable amount of RAM)