Is it fair to say that it was a bit of a sales pitch?
When key components of the ecosystem that were written in the language of the ecosystem itself are being rewritten in other languages - I think it’s hard to find a more compelling evidence that all is not as great as it was advertised.
I am sure no-one ever claimed that things (properly) written in JS are as fast as things (properly) written in C, Go, or Rust, and running in a native environment.
JS on the server may have been faster than php or python, due to the non-blocking nature of the event loop; but even that may not be the case anymore.
Generally, the pitch has been that js is "fast enough" for most tasks.
Yeah. It’s in the order of 4x slower than Java for most things, but it’s also like 100x faster than Python.
It’s all a matter of perspective, but in general, JS is probably about the slowest language I’d be inclined to reach for for long term solutions.
I get that VSCode might not be performant for others. I'm on a M1 Mac with 32gig of ram. I never notice any slowdown compared to any other editor I've used. I'm not saying other editors aren't measurably faster. I'm saying I don't notice any issues personally.
a) It's actually calling some native code internally (i.e. rust, c/c++ or V8 internals)
b) JIT'ed
Path "b" is very hard to achieve in CLI tool
Why say that?
Yes, perhaps if the CLI tool is being invoked many many times in succession.
But otherwise JITing isn't an issue: either (a) your program runs quickly in which case the Ignition interpreter is used and the JIT is not used, or (b) your program runs slowly in which case JIT (Sparkplug/Maglev/Turbofan) has time to warm up.
Each execution will be a fresh VM though. A CLI tool isn't a long-running daemon. There is also the whole lack of parallelism without forking in this ecosystem.