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Comment by steveklabnik | Hacker News Reader

If Rust is significantly slower than equivalent C or C++, it's a bug. Please file them.

(And yes, sometimes, it's faster. Today. Not always! Usually they're the same speed.)

My point is more like this chart [0]. C has so much lead time, Rust will probably never be able to catch up, be close? Sure. But C has decades of lead time.

[0] http://www.viva64.com/media/images/content/b/0324_Criticizin...

That chart is extremely old. We are sometimes faster than C in the benchmark games, with the exception of SIMD stuff due to it not being stable yet. (and, it can fluctuate, depending on the specific compiler version, of course.)

For example, here's a screenshot I took a few months ago: http://imgur.com/a/Of6XF

or today: http://imgur.com/a/U4Xsi

Here's the link for the actual programs: http://benchmarksgame.alioth.debian.org/u64q/rust.html

Today, we're faster in C than one program, very close in most, and behind where SIMD matters.

  > But C has decades of lead time.

Remember, Rust uses LLVM as a backend, which it shares with Clang. So all that work that's gone into codegen for making C programs fast also applies to Rust, and all of the work Apple and whomever else is working to improve it further, Rust gets for free.

I mean true, I'm playing devil's advocate here. I respect the Rust community (heck of all the nu-c languages I respect it the most, I even did a poster on 0.1 of it for my programming languages class), I will be quite impressed if they can pull off (and they are the most likely to be capable of it in my opinion) what so far has been an insurmountable task: beat an old guard language in general purpose performance (Fortran, C, etc.); languages that have every advantage but design foresight. If they do it, it will be a great historical case study on how to build a new programming language.

As an aside: As someone who has used LLVM to build a compiler, it doesn't quite work that way, yes rust has access to those gains, but it may not be able to effectively use them (due to differing assumptions and strategies).

Totally hear what you're saying on all counts :)

> My point is more like this chart <

As steveklabnik noted that is old data (which you would be normally be able to see from the date-stamp in the bottom-right corner, but that's been hidden).

This web page is updated several times a month, and presents the charts in context --

https://benchmarksgame.alioth.debian.org/u64q/which-programs...

(You might even think that you can tell which language implementations don't have programs written to use multi-core and which do.)

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