I am really off the PHP train now, but I'd also recommend to have a close look at http://www.phalconphp.com/en/ .

Their approach is to have the whole framework compiled as an extension. Seems well documented.

Personally, after years of dealing with PHP and the regularly occurring panic when inevitably something is going wrong during deployment, I'd consider PHP's dependency on other moving parts a bit of a nono. There's just too many pain points around deployment, versioning, server conf, extensions that are compiled in etc. Admittedly this has gotten much much better since the advent of composer and tools like chef, vagrant etc, but that's another whole learning curve right there. Compare that to go, where you just compile your binary, scp that up and then launch it. Done!