[Joker_vD]

> That’s not cache-friendly, though.

How so? The string implementations in that post are pretty much that:

    struct string
    {
        char* ptr;
        size_t size;
        union {
            size_t capacity;
            char buf[16];
        };

The pointer and the size are stored together, and they may optionally be located right next to the string's actual data, but only for very small, locally-allocated, short-lived strings; but in normal usage, that pointer points somewhere into the heap.

[Someone]

> they may optionally be located right next to the string's actual data, but only for very small, locally-allocated, short-lived strings

Only for small strings. Locally allocated and short-lived aren’t required for short string optimization to take an effect.

Also, I can’t find a good reference, but “only for small strings” in many programs means “for most strings”.