Just some remark ab read only 4Ko header http include and launch a new call, see source code. This is not a human behavior. You don't use keepalive, so you test essentially timing to get new connection. Nobody use web server with default configuration and no module. This sort of test could be more interresting with configuration following Apache recommendations, with some modules like apache+mod_deflate+mod_php+mysql, and another perf tool like httperf or better siege.