Sorry if I'm being picky, you were doing 1000 requests with requestHTTP above, your ab -n 500 will make 500 requests. Did I understand correctly the parameters
It is ok. I should have been more clear. The number of requests for both is 500. I have to say that the test is not completely fair, because ab is using HTTP 1.0 and the requests are a little bit different. But I still believe that they are indicative of a problem somewhere.