This is yet another benchmark to compare different hash tables (hash maps) with different hash functions in C++, attempting to evaluate the performance of the lookup, insertion, deletion, iteration, etc. on different datasets as comprehensively as possible.

We show the performance of hash tables with hash functions for different operations on different types of datasets of different sizes. The reader can refer to these results and choose the hash table and hash function that best match the target application.

The benchmarks were collected in 2022–2023 (machine configurations are listed below); this writeup was compiled and published in 2026.

The 24 byte string lookup test.

The 64 byte string lookup test.

The 12 byte string lookup test.

The integer key iteration test.

The integer key erase and insert test.

A full walk-through of what the benchmark showed — across both integer and string keys, small and large values — and how to turn it into a concrete choice of hash table and hash function for a particular workload.

This page discusses the memory usage and load factor of hash tables.

The integer key lookup latency test.

The integer key lookup throughput test.