[dkhenry]

This has less to do with the language and more to do with the ecosystem. If you ever get to a point where you need to extend the language your out of luck with PHP. Sure for most PHP users who cares they are just using it as a glorified CGI interface ,but if your building a product off it think twice you will reach a point where you will either have to rewrite everything or wade through the undocumented internals of PHP.

[Produce]

If it's such a big deal to you, why don't you contribute some documentation?

[btown]

Or, you know, rewrite the entire engine so it compiles into native C code or something. The fact that Facebook found that task preferable to hacking on the undocumented internals for performance says just as much.