Callbacks are often not the best approach. How about "inverting" the control by having a function which first collects all the elements to act on and then acts

Callbacks are often not the best approach. How about "inverting" the control by having a function which first collects all the elements to act on and then acts on them? This should prevent problems with cache misses since you perform only one kind of thing (on all elements) at a time. Where this kind of reordering is possible. (The callback approach is OOP I would say. And as always, OOP prevents us from seeing the better way to structure processing).