The problem is that most dynamic languages (like JS) are never designed with speed and efficiency in mind. JS just happens to be the fastest of that bunch (other than Lua) because browser makers have invested substantial effort into making it fast - far more than anyone has put into other dynamic languages.
However, JS specifically was not designed at all to begin with, but just thrown together, and core concepts have stayed since this first iteration. These core concepts are its primary handicap.
But yes, in general the same lack of static guarantees that makes dynamic languages slow also makes code in dynamic languages hard to maintain. I think a lot of programmers tinker with code in dynamic languages and end up liking them as a result, but don't realize the difficulty of working in such a language in a much more complex codebase.
I love Lua personally, but it has its own traps too. Never could get into Python too much, the indentation syntax is killing me :P
I no longer see dynamic languages useful for more than bash-like scripting where correctness is uninteresting. :/
Outside JS, most compiler work goes into static languages (which I strongly prefer), but once WebAssembly DOM support comes through, better languages will run on V8, stripping JS of everything it has.
This is a bit hyperbole. It could be worse, it could be python. Yes pypy does not have the investment of v8, but there is more to it than that. Yes js sucks but the language was relatively simple enough to get speedups that would not be possible in jitted python because frankly python is a steaming hodge lodge pile of shit when you take the system as whole (imnsho)
This in no way argues against some other languages being better designed for performance. Indeed, many other languages are better designed for performance. The designers should get recognition for the contributions they have made, as well.
Again, though, it can sound like disappointment that we can't get both teams working together. I contend that is short sighted. Yes, we can imagine a world where they worked together to make even better things. However, don't let that imagined world stop any communication on the front lines that we have today. (That make sense?)
