Golang folks, after looking at the code, I am surprised and don't understand why Go version is slow compared to C/C++/Rust. Can anyone please explain? Thank you.

Go's int defaults to 64 bits on a 64 bit machine while C/Rust/Java are all defaulting to 32 bit on the author's machine.

Editing the code and running local to get a difference factor, it looks like the same Go code with int takes 1.5x the amount of time as the int32 code on my machine. That puts it ~right next to Java (assuming the perf change maps 1:1). Remove the GC and it comes in ~right next to C++.

Looking at the compiler assembly output on Godbolt it's fun to see all the extra panic info and checks Go adds before going to the loop whereas the C just segfaults from blasting forward anyways, sometimes with no detail.

Anyways, that's why I don't like these types of "benchmarks" (micro tests made into a media post). By the time someone actually looks into them to see what's up everyone has already seen the results and moved on.

Author here: Yeah, I was surprised that there doesn't seem to be many options for extra optimizations in the Go compiler. Would be curious if Go experts have more insight or other compiler recommendations.