Intel tells you this in their optimization manuals and white papers. They want you to write code that takes advantage of their speedups. Agner Fog is a better

Intel tells you this in their optimization manuals and white papers. They want you to write code that takes advantage of their speedups. Agner Fog is a better writer (a sibling comment already linked to Agner Fogs stuff). But I also like referencing the official manuals and whitepapers as a primary source document. Hard to beat Intels documents on Intel chips after all.