hashbrown

It's still pretty major, because SIMD, but not as dramatic https://github.com/Amanieu/hashbrown#performance Note that the hashbrown crate uses FxHash by default, so the second table is the fair comparison. When ported to the stdlib it will likely be changed to have SipHash as the default. For the standard hashmap, replacing SipHash with FxHash gets you a 4x perf boost. Replacing the standard hashmap with hashbrown gets you a 2x perf boost (when you're using FxHash, there are no numbers here for when you're using SipHash but I suspect it will still be significant, if smaller)

Try hashbrown. Author declares 8x improvement over standard HashMap. https://github.com/Amanieu/hashbrown https://blog.waffles.space/2018/12/07/deep-dive-into-hashbro... https://gankro.github.io/blah/hashbrown-insert/