如何使STD :: MAP不需要两次比较整个字符串？

Question

std :: Map通过检查要搜索的值是否小于与当前比较的值进行比较，因此，这意味着如果MAP键是字符串，则将如果它们相等，需要将整个字符串进行两次比较。

我试图通过记录最后一个字符串来解决这个问题，并使用最后比较的结果，如果字符串相同。问题是我很确定这不是线程安全的，所以我认为每次使用MAP时，我都需要使用锁定。

有更好的方法吗？

#include <iostream>
#include <chrono>
#include <string>
#include <map>

const char* lastComparedlhs = nullptr;
const char* lastComparedrhs = nullptr;
int lastCompResult = 0;

struct ComparerForMap
{
    bool operator()(const std::string& lhs, const std::string& rhs) const
    {
        if (rhs.data() == lastComparedlhs && lhs.data() == lastComparedrhs)
        {
            lastComparedlhs = nullptr;
            lastComparedrhs = nullptr;

            return lastCompResult != 0;
        }

        lastComparedlhs = lhs.data();
        lastComparedrhs = rhs.data();
        lastCompResult = lhs.compare(rhs);

        return lastCompResult < 0;
    }
};

int main()
{
    std::map<std::string, int> normalMap;
    std::map<std::string, int, ComparerForMap> specialMap;

    std::string str1(10000000, 'a');
    std::string str2(str1);
    
    normalMap[str1] = 123;
    specialMap[str1] = 123;

    auto start1 = std::chrono::high_resolution_clock::now();
    int n1 = normalMap[str2];
    auto stop1 = std::chrono::high_resolution_clock::now();
    auto duration1 = std::chrono::duration_cast<std::chrono::nanoseconds>(stop1 - start1);

    auto start2 = std::chrono::high_resolution_clock::now();
    int n2 = specialMap[str2];
    auto stop2 = std::chrono::high_resolution_clock::now();
    auto duration2 = std::chrono::duration_cast<std::chrono::nanoseconds>(stop2 - start2);

    std::cout << "normalMap: " << duration1.count() << '\n';
    std::cout << "specialMap: " << duration2.count() << "\npress enter to exit\n";

    // normalMap: about 4000000 ns
    // specialMap: about 2000000 ns

    char ch = getchar();
}