Share your experience!
My phone is hanging while i play games like subway surfers and angry birds...also sometimes problem in swiping the application menu!!
Have you tried updating/repairing the phones software? You can do that using a computer and the USB-cable. See http://www.sonymobile.com/global-en/software/phones/xperia-j/ for update.
If you want to make a repair of the phones software, download Bridge for Mac or PC Companion from http://www.sonymobile.com/global-en/support/phones/xperia-j/.