closed #2789: Adds a macro ‘’USE_STD_UNORDERED_MAP” for switching the implementation of Map<K, V> between using std::unordered_map and std::map.
Merge pull request #5128 from dumganhar/iss2789-perf-container

closed #2789: Adds a macro ‘’USE_STD_UNORDERED_MAP” for switching the implementation of Map<K, V> between using std::unordered_map and std::map.