so I entered a world and set a fire on a tree and then set the tick speed to a very big number the fire did not  spread then I turned the tick speed a very big negative number nothing happened then I noticed a problem when the wolfs on my screen was not moving  I found a horse I dug a hole below the horse and the horse did not fall down then I thought it was a bug so I saved the world and I waited 1 minute it was still saving world so I pressed the x to close minecraft but nothing happened it took like 7 minute for it to close