Zoombie936

So I downloaded the mod pack "Crazy Craft Ultra" and it worked until something happened. Everytime I loaded a world in the pack it took about 30 minutes to load and then crashed. Not knowing what was wrong, I played around with the settings figuring that my computer couldn't handle the pack anymore. I didn't believe that because it worked fine on 1gb of RAM and I had given it 3gb. So I finally got the world to load only to find that there was a million cassowaries in the one spot and couldn't not type in a command to kill all the cassowaries due to the enormous amount of lag. Eventually it just crashed. So I was wondering if there is any way to edit the files in order to remove the mobs. I am OK with looking through files and seeing problems so if I could be directed to a location of where the mobs are kept and what to do that would be awesome. If that is not possible please say another solution other then deleting my world because I had some alright stuff in it.