Modern PHP is one of the best places to be doing web development in 2015.
PHP has a huge external perception bias from how awful it was up to 2011, and it doesn't help that 80% of PHP programmers you will run into are woefully unaware of modern PHP tools and techniques so they keep writing mangled messes.
Sculpin wraps the really nice templating engine Twig and you basically get all the features it provides, and the extensibility is really powerful. Sculpin let's you leverage all the components and packages for templates, i18n and perhaps more complex use cases.
I'm not sure why you want speed for generation of static content but if that is a constraint... I doubt that you will find better performance in node or ruby over PHP5.6 or PHP7.
So... PHP has the features, speed, and packages. What's the reason not to pick it? The syntax?