I like the article, and I like that the author gives specific details regarding the compiler and target machine, but trying to analyze performance at this level based only on C++ source code seems like a hopeless task. It's much easier if you remove the uncertainty of the compiler and analyze the assembly that computer is actually running, and then determine the specific factors actually governing performance.

Here's my strained analogy:

Assume that you wanted to write poetry in English with the goal of getting great reviews from English speaking critics. But unfortunately, you don't speak any English. So instead you write poems in your native language, and then feed them through Google Translate. The critics read the machine translation, and give their review as a single score. Based on that single data point, you try to determine how best to modify your native language poem to improve the score. Once you can no longer make progress, you publish your native language poem and encourage others to test the results with different critics and different machine translators.

Learning assembly is much easier than learning English. You still have to deal with the differences between processors, but removing the layer of translation makes optimization a much easier task. You can still write the final algorithm in a higher level language, but with a target in mind for the output you want, and with knowledge of the level of performance that is possible.