My iPhone 4s keeps freezing?

Anytime i go on appworld it freezes.

This happened to me, and apple nor future shop where i bought it from would fix it because it wasnt covered under their warranty. I jailbroke it and it fixed everything for me, no more app crashes, no more freezing/random rebooting, and best of all, you can actually use features that every other phone has! Its also arguably more secure.

Take it down an apple shop and let the Genius Bar people fix it.

or find the APP that is faulty. And delete it!

You could try backing it up
and then doing a full reset (delete all) from settings menu
Then
- restore the data
- re-load the apps (go to apps and not stored on phone and download)

you will have to re-arrange the icons again, their positions don't get kept (yeah wierd!) but iTunes does have a layout editor.