There's actually two problems: javascript vs. machine code generated from c (or a c-like) rebuilding UI elements in HTML and rendering them with a browser eng

There's actually two problems: javascript vs. machine code generated from c (or a c-like) rebuilding UI elements in HTML and rendering them with a browser engine vs. native UI toolkit. Often in comparisons the emphasis is only on the first one, and the difference usually isn't that big (maybe a factor of 2). The real issue actually is the second problem, it's much worse. That's also why I find the trend to do user interfaces in HTML so terrible: native UI toolkits work better and use less resources. The only advantage is that they run everywhere, but so does drawing into a 2D pixel matrix and rendering it.