@tvytlx: The father of Rails, DHH, had an agent rewrite his company's chat software Campfire once each in Elixir, Go, and Rust. …

The father of Rails, DHH, had an agent rewrite his company’s chat software Campfire once each in Elixir, Go, and Rust.

For the same room page, requests per second it can handle:
Ruby 244
Elixir 722
Go 3860
Rust 36260

That’s a difference of nearly 150 times.

This guy’s been saying the same thing for years:
Ruby is slow, but it’s fast to write and fun to write, and programmers’ time is more expensive than servers.
Rails was built entirely on that equation.

Then he added:
“But what if you’re not reading code anymore?”

That line made me pause for a second.

Ruby’s elegance takes care of people.
People need to read it, modify it, write it happily.
If agents take over writing code and verifying code, the benefits on the human side shrink, while the costs on the machine side don’t drop a bit.

I think the criteria for choosing a language will slowly shift from “which one’s comfortable to write” to “which one’s cheaper to run.”

Of course, don’t take this set of numbers too seriously.
He himself said speed isn’t the only factor—Rust’s slow compilation is a real hassle.
Someone in the comments said the 10x gap between Go and Rust is abnormal, probably because a few versions weren’t tuned to the same level.
For write operations like sending messages, the gap between Ruby and Rust narrows to about 27x.

But the direction is pretty clear.
The “a bit slower but people are happy” equation assumes people have to live in the code every day.
That assumption is starting to wobble.

The folks who got scared off by the Rust compiler back in the day can finally say with a straight face they don’t have to learn it anymore.
After all, the agent’s taking the scolding for me.

DHH (@dhh): I’ve had agents implement and optimize the Campfire web app in Elixir, Go, and Rust. Yes, Ruby is the slowest. I didn’t care about that when the pay-off was huge in terms of productivity and developer joy. But if you’re no longer reading the code?