Comment by cosmic_cheese

How it performs with existing JS doesn’t really matter in the context of my post, though.

For a “lite web” browser that’s built for a thin, select slice of the web stack (HTML/CSS/JS), dragging around the heft of a full fat JS engine like V8 is extreme overkill, because it’s not going to be running things like React but instead enabling moderate use of light enhancing scripts — something like a circa-2002 website would skew toward the heavy side of what one might expect for a “lite web” site.

The JS engine for such a browser could be trimmed down and aggressively optimized, likely even beyond what has been achieved with MQJS and similar engines, especially if one is willing to toss out legacy compatibility and not keep themselves beholden to every design decision of standard JS.