Even 5% sounds sketchy indeed. However, AVX2 (or Haswell New Instructions) hasn't quite been on every Intel processor this decade, rather only since the 4th gen

Even 5% sounds sketchy indeed. However, AVX2 (or Haswell New Instructions) hasn't quite been on every Intel processor this decade, rather only since the 4th generation (late 2013), and only in Core-branded processors.