> All code is perf-sensitive.

I'm doing some for loops in bash right now that could use 1000x more CPU cycles without me noticing.

Many programs use negligible cycles over their entire runtime. And even for programs that spend a lot of CPU and need tons of optimizations in certain spots, most of their code barely ever runs.

> Also, literally every language claims "only a x2 slowdown compared to C".

I've never seen anyone claim that a language like python (using the normal implementation) is generally within the same speed band as C.

The benchmark game is an extremely rough measure but you can pretty much split languages into two groups: 1x-5x slowdown versus C, and 50x-200x slowdown versus C. Plenty of popular languages are in each group.

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otabdeveloper4 5 days ago | parent [-]

> I've never seen anyone claim that a language like python (using the normal implementation) is generally within the same speed band as C.

Live long enough and you will. People claimed it about PyPy back in the day when it was still hype.

	▲	Dylan16807 5 days ago \| parent [-]
		Pypy is not the normal implementation. I was specifically excluding special implementations that only do part of a language and do it much faster. Especially with something like pypy that has extremely good best case scenarios, people can get too excited.