It depends on what is actually being benchmarked though; if it's the simple JSON payload, more time will be spent on HTTP parsing (done in nginx for the PHP benchmark so really really fast) and some JSON parsing (done in a C library for the PHP benchmark so really really fast). Basically, how much PHP is actually being benchmarked?

Are you looking at a benchmark that compares real-world usage, or a microbenchmark like hello world or a small JSON payload?