Comment by eyelidlessness | Hacker News Reader

Comment by eyelidlessness | Hacker News Reader

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You might be surprised how much startup time factors in. The last “blazing fast” Node test runner I tried had something like ~300ms of fixed overhead just to even start running a single test. None of that overhead is reported in stats, which is kind of understandable because it’s timing your tests, not itself. But 300ms just to get started measuring is a bit much IMO.

Anyway. Last I checked Bun still handily beats SWC (and ESBuild) on basically everything, and beats Node on tons (all?) of runtime metrics. Perf has been its foundational principle from the start, and every aspect of what’s under test in the article has been specifically mentioned as optimization targets by Bun’s creator. You’ll find many of your questions answered on his Twitter[1].

One thing I think is worth adding is that Bun’s perf obsession has been percolating a lot of optimizations upstream to WebKit/JSC. So even if you don’t ever adopt Bun as a server runtime, you or your users are likely benefiting from those contributions on the client.

1: https://twitter.com/jarredsumner?s=21&t=ZMU7ao_SpJj349QDow0M...

I changed some code for a tool to use worker threads instead of child spawn. We had libraries that could talk to services, and the tool’s job was to compare prod and preproduction, so the simplest thing to do is start two processes configured for both.

But the call time had gone north of 1 second so there was a lot of friction to adding more questions. I subsequently fixed some dumb bootstrapping code to the tune of ~250 ms, which would have been enough to add all of our current apps to the tool, but what really helped was using worker threads knowing the number of environments to check was finite. We only needed k threads so we could eat startup time entirely.

Bun is also faster. If you added my fix and used Bun, you could use forking to cover cases that are O(m) instead of O(k). (Typically k << m < n when doing orders).

> Last I checked Bun still handily beats SWC (and ESBuild) on basically everything

What did you check? Bun only has basic transpiring currently. I can't imagine what "everything" is, and without bundling, minification, and down-transpiling support I don't see how any meaningful project could have been tested on.

> Bun’s perf obsession has been percolating a lot of optimizations upstream to WebKit/JSC

Source? AFAIK claiming either "bun devs made a lot of JSC perf optimization PRs" or "bun devs pointed perf hot spots to JSC devs" would be incorrect, but I'd love to learn otherwise.

> Bun only has basic transpiring currently. I can't imagine what "everything" is, and without bundling, minification, and down-transpiling support I don't see how any meaningful project could have been tested on.

Yeah, build/bundling use cases have lagged in priority. I’ll rephrase “everything” as “every transpiling use case”.

> Source? AFAIK claiming either "bun devs made a lot of JSC perf optimization PRs" or "bun devs pointed perf hot spots to JSC devs" would be incorrect

Jarred’s Twitter has been frequently highlighting these contributions. This seems like a weird thing to object to if you’re so familiar with the project!

The highlighted contributions you're referring to are from day-to-day work by core JSC contributors/Apple employees.

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