I feel like the article “c is not a low level language” is worth linking here.

Once you start to dig into how computer hardware really works, you start to realize that nothing is really O(1).

If you’ve never looked into computer hardware, you’d believe that lots of the primitive machine operations like reading and writing a value are O(1). But on modern hardware, they can be far slower. And that’s before we even get into out of order instructions etc.

So by the authors definition, I guess assembly and machine code aren’t real systems languages ;)

https://queue.acm.org/detail.cfm?id=3212479