In fairness, it is eminently possible for one bad application to stomp all over another one. The OS tries to guard for this (and has some trivial protections such as guarding the red zone), but there really isn't much true protection at all.

That said, as you demonstrate, a well-chosen set of well-behaved apps will run faster and just as well on a real-memory, cooperatively multitasked OS simply because preemptive multitasking and true virtual memory cost cycles. But then, cherry picking always works. }