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This is not just because of algorithm and data structure though, it's also very well implemented

>It also means that having tools where you can quickly apply different techniques, ahem, composable functions

The key word there is composable, and not functions.

The points of discarding data you don't need, not looking at stuff you don't need to look at, and minimizing the processing of the stuff you do look at are also highly valid.

I've seen 90% performance boosts in code where access to low-level data formats really wasn't possible. Though at times, using appropriate data structures / methods also helped markedly.