There may be contrived situations where std::map<T> is actually faster due to the operator < work being possibly cheaper than doing the full hash of the key, bu

There may be contrived situations where std::map<T> is actually faster due to the operator < work being possibly cheaper than doing the full hash of the key, but that will only work if the key type is very well distributed early on in the key (i.e. for very long strings, with the first few characters in long strings all being different among items in the std::map, providing the ability to short-circuit quickly) and the number of items in the map is less than what's needed to meet the short-circuit threshold that makes it technically more efficient. But that's very unlikely, and in such a contrived scenario it's likely doing a linear std::find() over an array of keys would be as fast or faster anyway, due to better caching/pre-fetching/branch-prediction.