Note that this benchmark does not include boost::unordered_flat_map. This is an open addressing variant of boost::unordered_map which has only been released in December 2022.

I wanted to mention this because boost::unordered_flat_map and boost::unordered_flat_set are among the fastest open addressing hash containers in C++ land. Internally, they use lots of cool SIMD tricks. If anyone is interested in the details, here's a nice blog post by the developer: https://bannalia.blogspot.com/2022/11/inside-boostunorderedf...