If compiling 7 lines of code in release mode takes few minutes in Rust, just like it does in Crystal (I don't know exactly how long, I got bored and gave up, so it's possibly more), then I wouldn't touch that language with a ten foot pole either. It's fine to make trade-offs, it's just not a trade-off I'm personally willing to make. As to the productivity thing, it's debatable I guess.