Languages performance

If it's the same engineer, with roughly equal skill in both rust, and an interpreted language like java or javascript, it's likely rust will go faster. It's not totally unreasonable.

Hotspot claims notwithstanding, interpretation imposes a noticeable overhead, and GC, even the latest ones in java 17, still gets you with tail latencies. And in k8s, I've even seen the overhead from java running (relatively speaking) like molasses until most of the classes are loaded, impact how you provision autoscaling.

If it's two different engineers, with different skills (particularly if the first is gone, and the new one has less experience in the given domain), then, yeah, making a blanket statement like "rust will be faster" is questionable.

As far as maintainable, yeah, it's a curate's egg, that one. I love the Rust language, the language itself is reasonably mature, but the existing libraries / frameworks for web serving are very immature.

I like Java (although people abusing Optionals and Streams is getting tiresome, basically autocomplete encourages people to stop making methods, and just chain a bunch of fugly lambdas together, and Spring *sigh* I use it, but *sigh*, known bad practices, per the Spring engineers, are still endemic to Spring code), but the frameworks & libs are better than what Rust has.

Javascript is alright. Particularly in terms of ExpressJS being at pretty much the perfect level of abstraction for how I think. But even with async / await, callback hell persists. And nodejs can have impressive performance.. until it doesn't, and it's still overhead you won't have in Rust.

So, without context, if someone says "Rust will be faster".. hey, they might be right.