Python is slow.

I started working with Ruby almost two decades ago and I can confirm that, in fact, Ruby is slow. It might be fast enough to make it viable for most web apps, but compared to Go or Rust it will be much harder to write a fast app in Ruby. I've seen tweets and articles like this one (it's the databse not Ruby!) numerous times and it usually doesn't map to reality, especially in bigger applications. Of course you can make Rails to respond in milliseconds, but in real production apps I've usually seen 50-80% of the responses time to be spent in CPU (ie. Ruby). At the same time when the app grows and you add more middleware an empty response can easily take 5-10ms with a bit of a traffic (like: an empty controller action, no database queries etc). It's better with smaller frameworks like Sinatra, but still you can make the database much faster than the Ruby code making queries

update:

Maybe out of curiosity I'll make some benchmarks later, but even if you look at frameworks benchmarks you can see that for the same database queries there's an order of magnitude of difference between Ruby and Rust or Go frameworks: https://www.techempower.com/benchmarks/#section=data-r21&tes... (look at latency)

> Ruby3 was faster than python at some point, iirc

That’s the lowest bar for performance.