I want to add turn physics on button in my game editor, something similar to Havoc button in TES Construction Set (something like this: http://youtu.be/6RzxXWiqb8M?t=7m40s). It's job would be to make the objects I've placed fall into desired natural position. Unfortunately, I cannot find any mechanism that would let me simulate only a part of Box2D world and since my world is pretty big this can cause unwanted changes.
Is there any way to do it? I haven't found any suitable answer on the internet.
So far I've only thought of manual bodies deletion before simulation, but seriously this is a lot of work, probably not needed.