I'm not sure I would frame unused memory as "waste". At least not necessarily. If the system is operating below max capacity, that memory isn't wasted - it's a reserve capacity to handle surges. The behavior of the system under load (when it matters) might very well depend on that "wasted" memory.

You want to compare the _maximum_ memory under load - the high-water mark. If you combine Wozz with a benchmark to drive heavy traffic, you could more confidently say any unused memory was truly wasted.