Zend Optimizer Plus - still not following the party line

Having previously failed to get a significant difference in benchmarks between PHP 5.3 and 5.5, I was successful in establishing that the optimizer was producing code which ran slightly faster (about 2% with DokuWiki).

This time I tried ramping up the concurrency to see if PHP could deliver on its performance promises.

Running

ab -n 12000 -c $X http://localhost/src/doku.php

For $X in [10,50,100,200,300,400,500,600,700,800]  I got....

For less than 500 concurrent connections, PHP 5.3.3 is slower - but only about 5%. At more than 500 concurrent requests, 5.5.1 is slower!

I'm just no good at this benchmarking business.

Both were running from nginx+php-fpm with the same (common) config. 5.5.1 had full ZOP+ optimization enabled.