Twice as fast at executing JavaScript? There's absolutely zero chance this is true. A JavaScript engine that's twice as fast as V8 in general doesn't exist. There may be 5 or 10 percent difference, but nothing really meaningful.

You might want to revise what you consider to be "absolutely zero chance". Bun has an insanely fast startup time, so it definitely can be true for small workloads. A classic example of this was on Bun's website for a while[1] - it was "Running 266 React SSR tests faster than Jest can print its version number".

[1]: https://x.com/jarredsumner/status/1542824445810642946

Keep in mind that it's not just a matter of comparing the JS engine. The runtime that is built around the engine can have a far greater impact on performance than the choice of v8 vs. JSC vs. anything else. In many microbenchmarks, Bun routinely outperforms Node.js and Deno in most tasks by a wide margin.

It depends on what. Bun has some major optimisations. You’ll have to read into them if you don’t believe me. The graphs don’t come from nowhere