> I don't think the machines that Dillo is targeting would benefit from adding support for it

People tend to overestimate the resources required to run JS and have a miscalibrated sense of how slow they can/should expect it to be.

Firefox 1.x and 2.0 worked on machines with substantially worse specs than many of the ones that people are mentioning here (think: sub-GHz PIIIs with 128–256 MB of RAM), and substantial parts of Firefox itself are written in JS.

I haven't checked, but I'd bet that 2024-era QuickJS is also faster than 2004-era SpiderMonkey at executing the same script.