Over every entity system I see implemented in C++, or even in Java/C# (e.g. the Artemis framework). I see components not allocated via a new operator (or something similar, e.g. std::make_shared). For example:

entity.addComponent(new Position(32, 4, 5));
entity2.addComponent(new Position(5, 6, 7));
// those two position components that were just created
// may/may not be together in memory

// or even:
// how can you avoid using new here? (in the implementation)
entity.addComponent<Position>(32, 4, 5); 

Doesn't this harm performance, as there would be cache misses (since new can allocate data anywhere from the heap)? How would you implement a system in such a way that the components of each type are allocated contiguously in memory, so you avoid cache misses? I mainly want to know how one would do so in C++.