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Why is Mozilla Firefox written in Rust, then? The last time I looked at browser benchmarks was in 2016 when Google released benchmarks to brag about its perfor

Why is Mozilla Firefox written in Rust, then? The last time I looked at browser benchmarks was in 2016 when Google released benchmarks to brag about its performance over Firefox and Edge. It appears Webkit has released JetStream2 to benchmark JavaScript, WebAssembly and web workers, among other things. But I can't find data showing Mozilla Firefox is ~20% slower than Chrome/Edge today.

dthul 7y ago
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.
- pdimitar 7y ago
  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.
- The_rationalist 7y ago
  Facts: On average rust is 10% slower on the banchmarkgame: https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/gpp-rust.html 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.
  - steveklabnik 7y ago
    > 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.
    - igouy 7y ago
      > 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/which-programs-are-fastest.html 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?
      - steveklabnik 7y ago
        > 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".
        The_rationalist 7y ago
        Geometric mean is the implicit default measurement for benchmarking
        igouy 7y ago
        typo ? "the colloquial term" is "average", the specific term is "mean".
  - igouy 7y ago
    > 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.
The_rationalist 7y ago
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-70-chrome-78&num=1 https://www.phoronix.com/scan.php?page=article&item=firefox-...

dthul 7y ago

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.

pdimitar 7y ago
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.
The_rationalist 7y ago
Facts: On average rust is 10% slower on the banchmarkgame: https://benchmarksgame-team.pages.debian.net/benchmarksgame/fastest/gpp-rust.html 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.
- steveklabnik 7y ago
  > 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.
  - igouy 7y ago
    > 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/which-programs-are-fastest.html 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?
    - steveklabnik 7y ago
      > 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".
      - The_rationalist 7y ago
        Geometric mean is the implicit default measurement for benchmarking
      - igouy 7y ago
        typo ? "the colloquial term" is "average", the specific term is "mean".
- igouy 7y ago
  > 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.

The_rationalist 7y ago

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-70-chrome-78&num=1 https://www.phoronix.com/scan.php?page=article&item=firefox-...