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Question: How is hashbrown faster than the stdlib HashMap? (self.rust)

submitted 10 months ago by BolshoyToster to c/[email protected]

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I'm curious as to how the hashbrown crate can have up to 2x performance on certain operations, even though it looks like the standard library's HashMap is just a wrapper for hashbrown.

I understand that a wrapper could add a small overhead, but 50% of the original performance is a bit silly, especially considering all of the functions in the wrapper are #[inline], so there should be no overhead in calling most functions.

Does anyone know the reason for this?

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[–] [email protected] 11 points 10 months ago

hashbrown uses aHash by default, which is much faster than std's SipHash-1-3