> The joke is that if Meta thought that replacing all the Python code they have with something else was worth it, they'd have done it already.

"Worth it" depends on both how much performance improvement you get, and how hard it is to replace. Did you consider maybe the rewriting effort is so humongous that it is not worth doing despite large performance improvements? Thus making the joke not funny at all...

That's exactly the joke though. Every time Ruby (or Python) is discussed on HN we get the same old tired question of "why don't they just rewrite in Rust".

But that's some silly engineer tunnel vision, squeezing the very last bit of performance out of a system isn't a goal in itself. You just need it to be efficient enough that it cost you significantly less to run that the amount of revenue it brings you.

I can bet you that moving off Python must have been pitched dozens and dozens of time by Meta engineers, but deemed not worth it, because execution speed isn't the only important characteristic.

So yes, I find it hilarious when HN commenters suggests companies should rewrite all their software into whatever is seen as the most performant one.

It's usually dismissed because companies think short term, and switching languages is a project with huge short term disadvantages and huge long term advantages.

It's usually dismissed because it's almost always a huge strategic blunder.

I think they meant Facebook switched their PHP code to Hack and HHVM, their own PHP-like language and implementation.