Why does an iPhone speaker stop working and the screen slows down like its lagging?

[tamarawilson112]

My bf has the iPhone 4S and he took it in to get it checked out because his earpiece or some speaker would not work and his screen was being slow, like it was a game when there are too many ppl on or like the internet on a Sunday. So, i guess i am asking, why does this happen, is there a prevention and is it fixable? The guy that he took it to said that it might not be fixable, so he may end up having to get a whole new phone and #.

 

[pkcable]

Did he update to iOS 9? It does not run very well on the 4S. Although it IS compatible it does not run well. Many folks have opted NOT to update.