Our SipHash-2-4 performance is sometimes odd.
Something is screwed up (probably in the code gen), such that hashing buffers that aren't a multiple of 8 has performance issues.
siphash24g(7): 30.42 ns per call
siphash24g(8): 22.67 ns per call
siphash24g(15): 34.08 ns per call
siphash24g(16): 27.14 ns per call
siphash24g(20): 36.35 ns per call
siphash24g(32): 37.66 ns per call
siphash24g(111): 93.87 ns per call
siphash24g(128): 100.21 ns per call
I'm not sure if deviating from the upstream further to fix this is the right thing to do, but we probably call this code a decent amount.