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IIRC you need to enable AVX-type instructions to really have SIMD:

-mavx2 -mfma -mavx512pf -msse4.2 etc

Author here. The original article I was going to write was about using newer instruction sets, but then I discovered it doesn't even use original SSE instructions by default, so I wrote this instead.

Eventually I'll write that other article; I've been wondering if it's possible to have infrastructure to support both modern and old CPUs in Python libraries without doing runtime dispatch on the C level, so this may involve some coding if I have time.

Yeah. And I dont mean this in a "no true scottsman" way. I really have trouble coaxing any kind of instruction-level parallelism w/o those.

There's presumably a reason they've spent the past 20 years adding additional instructions to CPUs, yeah :) And a large part of the Python ecosystem just ignores all of them. (NumPy has a bunch of SIMD with function-level dispatch, and they add more over time.)

Or alternatively, -mnative should do all of those and more if your CPU supports them

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