This needs a (2004). The article mostly targets the Intel Pentium 4. Many high-level tips still hold true (for example those that could apply to any programming language, like expressing divisions as multiplies), but quite a few things have changed since then. Especially things related to microcode are likely be different now.
Linked in the article is Agner Fog's website: <a href="https://www.agner.org/optimize/" rel="nofollow">https://www.agner.org/optimize/</a>. Which appears to have up-to-date knowledge and 2001's web aesthetic (just the way it should be).