Comment by benswerd

We're using copy on write with the memory itself. Fork time is completely decoupled from the size of the machine.

Creating snapshots takes a 2-4 second interruption in the VM due to sheer IO that we didn't want here.

Whats especially cool about this approach is not only is fork time O(1) with respect to machine size, but its also O(1) with respect to the amount of forks.