Using Firefox to evaluate Rust performance is probably not a good idea since only parts of it are written in Rust today.

But it's the first time I hear someone say that Rust is supposedly fundamentally slower than C++. I don't believe this to be a statement that can be substantiated, seeing that some of the fastest programs out there (ripgrep and hyper to name just two) are written in Rust.

Facts: On average rust is 10% slower on the banchmarkgame: https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

But they use llvm instead of gcc for c++, and gcc is in average 20% faster than clang. Therefore, rust is 30% slower, at least on heavily optimised programs.

And hyper is not the fastest http server, but the actix one is one of the fastest yes.

> Facts: On average rust is 10% slower on the banchmarkgame

That does not show it's 10% slower on average; it shows that C++ is 0.9917938291x as fast as Rust. They both have some where they win by 30%, most are closer, Rust is just faster on average.

> But they use llvm instead of gcc for c++,

C++ g++ g++ (Ubuntu 9.2.1-9ubuntu2) 9.2.1 20191008

?

> gcc is in average 20% faster than clang.

Extremely citation needed.

> faster on average

What kind-of time measurements? What kind-of average?

This chart shows some time measurements:

https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

:and the geometric mean is faster for the C++ programs, but the median seems faster for the rust programs.

Statistical artifacts?

> What kind-of time measurements? What kind-of average?

I interpreted the parent to mean a simple average, so I did exactly that: calculated the percentage for each, and averaged them. In the colloquial term, "mean".

typo ? "the colloquial term" is "average", the specific term is "mean".

Geometric mean is the implicit default measurement for benchmarking

> On average rust is 10% slower on the banchmarkgame

If that claim was true …

> gcc is in average 20% faster than clang

and if that claim was true …

then we might guess the rust programs average could be 10% faster than the C++ programs average, if both used the same compiler backend

— because those rust programs were compiled with llvm but those c++ programs were compiled with gcc.

IMO the jury is still out. I am pretty sure that C++ veterans that can cleverly utilise any and all performance tricks (minus resorting to an assembly language) and can thus beat any other language.

But I -- like yourself -- am much more interested in the applicability of a language in everyday tools, plus in getting the most performance with the least amount of dark magic involved.

BTW, `ripgrep` definitely made me work better and faster.

Firefox is far more than 20% slower than Chrome today but is not strictly a direct cause of using rust. https://www.phoronix.com/scan.php?page=article&item=firefox-...