That these performance hogs were in production reinforces my point that you can't spot slow code just by looking at it, unless you already know that it's slow.

That these performance hogs were in production reinforces my point that you can't spot slow code just by looking at it, unless you already know that it's slow. I even have an example myself, but I'm not sure I can share it in detail. It was a common idiom that was used throughout the code. After tracing a performance problem to a specific function, it was immediately obvious to me that the common idiom was the problem in this function, and how to fix it very easily. But only because I traced a performance problem to this function. Otherwise I would have skimmed over it.