Yep; the quote was originally about in line optimizations, like profiling to avoid cache misses and tightening inner loops and such. Nowadays, with your main co

Yep; the quote was originally about in line optimizations, like profiling to avoid cache misses and tightening inner loops and such. Nowadays, with your main concern being service throughput, the bigger concern is your architecture, not your implementation. Which is where the confusion is, possibly. Architectures you can't easily undo; that loop or choice of data structure you can. So it's generally worth giving careful consideration towards your architecture (it's not premature to ask "What happens when this one thing becomes two?")); it's generally not worth giving the thought towards your implementation.