Yep you are quite right. The optimiser basically does what an experienced C++ optimisation experts would (tediously) do by hand: it carefully reduces the number

Yep you are quite right. The optimiser basically does what an experienced C++ optimisation experts would (tediously) do by hand: it carefully reduces the number of reference counter modifications to an absolute minimum by symbolically evaluating the full executing flow of the code. It is something that is doable in a pure functional language like this one. I am not sure if it is possible to do the same in C++ (because of the aliasing rules).