When I tried to open my world, my game crashed. I'm not sure why, its only happened once before

I tried to open my world to play survival and as I did the game crashed.
My computer lags quite a lot and I keep re-opening the world to stop it from lagging too bad. It was about the 6-8 time I re-opened it and it crashed. It might just be because my computer sucks I don't know.