&gt; I think I can probably say that Javascript engines are an order of magnitude faster than they were 16 (!) years ago.<p>Two orders of magnitude.  I just checked, and on my laptop <a href="http:&#x2F;&#x2F;web.mit.edu&#x2F;bzbarsky&#x2F;www&#x2F;mandelbrot-clean.html" rel="nofollow">http:&#x2F;&#x2F;web.mit.edu&#x2F;bzbarsky&#x2F;www&#x2F;mandelbrot-clean.html</a> (the first JS thing I wrote where performance of the language itself seriously mattered) runs in about 30-60ms in modern browsers.  On the same hardware, it runs in about 2200ms in Firefox 3, which is the last pre-JIT version of Firefox.  Other benchmarks I&#x27;ve tried show similar improvements results.  And that&#x27;s only going back to 2008; the interpreter was a good bit slower another 8 years before that.