Something very relevant to this discussion was this article[0] from a few weeks back. A bit of a clickbait title, but the points are very relevant: C, based on the PDP-11, has a computation model that no longer really tracks with how a computer actually works today, and in those gaps is where people insert in stuff like speculative execution in the first place to be faster while maintaining the guise to app developers of a "fast PDP-11".
My favorite article on this: "C Is Not a Low-level Language: Your computer is not a fast PDP-11"
Hacker news post: https://news.ycombinator.com/item?id=16967675
and again: https://news.ycombinator.com/item?id=21888096