I read it such that if, for arguments's sake, Ruby is 10 times slower than Java that people would start using a new language that is 10 times slower than Ruby. I'm not sure that ever described Javascript, and it certainly didn't as the decade progressed with the advancements that have been made in executing it.

I feel like that one simply missed the mark. If anything, there was greater emphasis towards languages that were more performant, even if less productive for banging out a working product.

It definitely did. IE6's JavaScript was super slow. You cannot even imagine how slow it was if you never worked in it.

Remember, IE6 was the dominate browser for years, so very slow JavaScript was the norm.

For example round about 2008 I made a client-side pivot table for a web app, tried it in JavaScript first, even trivial tables would take 10 seconds despite all the optimization I tried (in IE6, IE7 + Firefox).

I rewrote it using XML + XSLT and it was instant. But it was truly gnarly code.

I think the point of the prediction is that the new, slower language would be more expressive. More natural-language-like. That doesn't describe JS.

People who have seen more than I have: how much slower were JavaScript in IE6 vs V8?