You should check out the framework benchmarks. Raw php is competitive with other web dev platforms performance-wise, but the major php frameworks slow it down by an order of magnitude. I blame the PSR / on-demand class loading java-style architecture which was adopted by all the frameworks. They've copied a java architecture into a platform that doesn't have java's performance characteristics.
In my own benchmarks i've noticed all that class loading and instantiation slows things way down, even with an opcache. I find that a namespaced procedural / functional architecture performs much better, but no PHP framework works that way.
In my own benchmarks i've noticed all that class loading and instantiation slows things way down, even with an opcache. I find that a namespaced procedural / functional architecture performs much better, but no PHP framework works that way.
http://www.techempower.com/benchmarks/