I guess the important difference is that std::min_element doesn't return the minimum value, but iterator for the minimum value.  Finding the element with minimum value is more expensive than the value itself.

If you write:

  auto mins = *std::min_element(f.begin(), f.end());

so that you ask for the value, the benchmark now says the perf is exactly the same for the 2 versions. I would close this as invalid.

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