The fastest and mostly-secure 64bit hash functions are Metro, Spooky, xxHash64 and Multilinear-HM by the same author. See "Strongly universal string hashing is fast", Daniel Lemire and Owen Kaser, 2014.
CLHash doesn't even pass the avalanche test from smhasher https://github.com/rurban/smhasher
I'll add it there for better comparison, with the new leader falkhash: https://github.com/gamozolabs/falkhash
Makes me think there's a lot more improvements to be had with the much larger and specialized instruction sets we're seeing nowadays.
CLHash, the hash the post is focused on, passes all except the avalanche test for strings <8 bytes, and could be made to pass it by adding a bit-mixing step to the end (that provably doesn't make random collisions more likely, since it's an invertible transform on the hash).