The short and to-the-point version of the post went to the Rails-core mailing list. On my blog, I prefer to tell stories.
There are quite a few stories of this nature, which could simply be summarized as individuals finding incredibly simple inefficiencies and then fixing them.
IME, many many developers have no idea how to measure and profile their code. The reason for the stories is to help educate people with less experience in what tools to use, and how to use them.
I'll admit that I don't know enough about this. Got any pointers or links for the intermediate Rails hacker? (I'll check out ab, as mentioned in your post.)
There are quite a few stories of this nature, which could simply be summarized as individuals finding incredibly simple inefficiencies and then fixing them.