It's no slower than Python. Probably faster unless you're staying within a native library like NumPy.

But that wasn't my main point: my main point is that people love to rant about "JavaScript apps" while maintaining (willful?) ignorance about what the actual factors are that manifest as the slowness they experience. Sometimes it's poor usage of the DOM. Usually it's ads. It's almost never the unavoidable overhead of JS cycles.

> people love to rant about "JavaScript apps" while maintaining (willful?) ignorance about what the actual factors are that manifest as the slowness they experience.

Are you sure you got this right?

Just because JS is fast[0] doesn't mean we cannot complain about Javascript apps that should have been plain web pages?

It is clearly possible to create advanced Javascript apps that are enjoyable even to people like me.

For most pages I use as a consumer I don't see much value add because of frontend code: I see the value of autocomplete, drag-and-drop etc but I would much prefer if my CPU stopped chewing after web pages were loaded and rendered.

[0]: yes, I agree - in most cases the Javascript language or engine is not the cause of the performance problems on the web

Whether or not a given site should be client-side rendered is a valid discussion

Ad bloat is a valid discussion

Lazy development practices in modern sites/apps are a valid discussion

But in my experience, these as well as other less-legitimate issues all tend to get lumped under the banner of "JavaScript stuff == slow", without any nuance.

Can't say for sure but the way I read them most complaints about Javascript performance are about the results of the abuse of Javascript applications everywhere.

I guess Javascript just happens to be the common thing between a number of them, and people would be just as annoyed if the multi-megabyte, cpu-hogging, data-stealing monstrosities where hand-crafted in assembly ;-)

And: If someone complained about Javascript being slow for scientific calculations I'd probably call them out on it ;-)

> but I would much prefer if my CPU stopped chewing after web pages were loaded and rendered.

this happens when it's programmed with performance as an afterthought, which is sadly how things work when the prerogative is to just ship more features and continually ingest dependencies with the most features, with little vetting.

Javascript is probably at least an order of magnitude faster than Python.

For me as a user it seems to be: loading google analytics, loading fonts that seem to be improperly cached, loading chat windows, assistance widgets and spies, and dynamically adding things after page load that cause reflows.