Game crashes and freezes causing me to lose all my items multiple times

The game is very laggy. At times it freezes completely for a couple seconds. Half of the time when I enter the end the entire app crashes. I am working on an enderman farm, and I have died from fall damage on two occasions, and both times my items were in a safe place. When I went back to get my stuff back the game crashed and it said there was an error in the application. When I finally made my way back to where I died (in only a minute or two in game) everything was gone. I have had that world for several months and I lost all of my good items. I am ready to give up on this world at this point.