Unity 4.2.2 .OBJ import crash

I want to use the same game engine used to make Slender: The Arrival (Unity 4.2.2) for my game The Chaser, which is a spin-off of the aforementioned game. I have a large environment (OBJ. file) similar to one from the game, but, every time I try to import it into Unity 4.2.2, it crashes when "Importing small assets". Can someone please help me or should I just use Unity 5 instead? Any help would be greatly appreciated. Thanks in advance!