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Comment by samnardoni | Hacker News Reader

Rust uses LLVM, which does all the optimisation. Go generates the machine code itself and its optimisation is pretty weak compared to LLVM.

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An older version of the benchmarks discussed on the Go mailing list was done with GCCGO (which I assume is Go with a GCC backend). Given that GCC is historically ahead of LLVM on CPU optimizations (a gap that has shrunk in recent years), I'm guessing that's not a complete answer.

But, if it is the primary source, it would tell me that Go will close the gap as the compiler becomes more advanced and takes advantage of more CPU optimization features. Also, it's an interesting difference that Rust is an LLVM language while Go is compiled to native code directly; probably not from a performance perspective (at least not in the long run), but from a development perspective...is it easier or harder to develop new language features on LLVM or a native compiler?

https://groups.google.com/forum/#!topic/golang-nuts/NSPcEqhe...

Note: despite the "VM" in the name LLVM is a native compiler: the rust compiler constructs the appropriate internal representation to LLVM and passes it to LLVM for optimisation and native code generation. There's not really a fundamental difference between this and writing the code generation step in pure Rust other than the latter missing out on all the benefits (speed, architecture support etc) of LLVM.

That is to say: there's not much difference for difficulty of developing new language features, but avoiding LLVM makes it harder to develop new fast language features.

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