[ MCPE 0.4.0 WORLD OPENING BUG ]

Everytime I open my 0.4.0 world on my RCA Voyager 1 on mcpe version 0.13.0 it lags then it crashes. It only lets me on it for about 3 minutes and then it starts to lag horribly then freezes, then it crashes. Please fix this because I had this world since 2012 and I finally revive it from my old tablet onto my new one.