Blog post: Is Rust faster than C? by Steve Klabnik

Steve Klabnik

Comparing Rust and C performance is complex because 'all things being the same' is difficult to define. While both languages can achieve similar performance through inline assembly and compiler optimizations, they differ in default behaviors like struct field ordering, bounds checking, and safety guarantees. Rust's compile-time safety checks may lead developers to write different code patterns than in C, affecting runtime performance. Social factors also play a role, as developers may be more willing to write performance-oriented code in Rust due to its safety guarantees. Fundamentally, there's no inherent reason Rust cannot match C's performance capabilities.

Is Rust faster than C?

Here’s a fun one from the past. I’m not that old; this is from Youtube videos: FORTRAN was effectively faster than raw hardware bytecode because, even though the FORTRAN interpreter was much slower than bytecode, bytecode took so long to write that the computers often sat idle. At that point, the programmer was the bottleneck.
And that’s why Python became popular in the hard sciences, and is still, so far as I’ve heard, popular today. It’s easy to write and can call fast math functions for very large calculations. Fast Python compilers and interpreters came later, after the language saw widespread adoption.
And then there’s video game scripting languages, which are often interpreted and have a simple API. The point is code that not only runs fast enough for the task, but also code that arrives fast enough to be useful. Which is no insult to artists; as a programmer, nobody is going to hire me for my art.
Anyway, just some thoughts on related matters.

The relevant question is: faster than which C compiler? Clang, GCC, msvc? Big difference.