AVX2 is slower than SSE2-4.x under Windows ARM emulation
Hacker News
February 18, 2026
If you compile your app for AVX2 and it runs on Windows ARM under Prism
emulation, is it faster or slower than compiling for SSE2-4.x?
I assumed it would be roughly the same — maybe slightly slower due to emulation
overhead, but AVX2's wider operations would compensate. The headline gives it
away: I was wrong.
💡TLDR: AVX2 code runs at 2/3 the speed of equivalent SSE2-SSE4.x optimised code
under emulation on Windows 11 ARM.
'Should I compile for AVX2 if my app might run on Windows ARM?' has a
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Originally published on Hacker News on 2/18/2026