Thank you! Indeed GCC does not use SIMD here unless you set -O3 (... I seem to remember this enables some vectorization?) or allow it to use AVX with -mavx or -

Thank you! Indeed GCC does not use SIMD here unless you set -O3 (... I seem to remember this enables some vectorization?) or allow it to use AVX with -mavx or -march=x86-64-v3. For some reason I’m unable to get it to use plain SSE (always available on x86-64) with any -mtune setting or even with -march=x86-64-v2.