Apache :: CentOS - Measuring Performance Of Server

I have centos -7 and apache 2.4.6. I have made one small php scripts and measuring the performance of server.

Average time is around 15 ms for per request. But when adding concurrent requests the average time increase too much high for the request see the below output

ab -n 10000 http://127.0.0.1/1.php

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 14 17 2.6 15 35
Waiting: 0 1 0.2 1 10
Total: 14 17 2.6 15 35

With Concurrent connections

ab -n 1000 -c 100 http://127.0.0.1/1.php See the processing the mean request time its around 150 ms.

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 1.1 0 5
Processing: 25 150 24.7 153 213
Waiting: 2 134 25.2 138 194
Total: 29 150 24.1 153 216

ab -n 1000 -c 100 http://127.0.0.1/1.php See the processing the mean request time its around 150 ms when total request is 1000 only.

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 1.1 0 5
Processing: 25 150 24.7 153 213
Waiting: 2 134 25.2 138 194
Total: 29 150 24.1 153 216

How to configure the Apache so the request time decreas to low ms ???

In Centos -7 Default configuration of MPM Directory also not found ??? checked in httpd.conf and other file also.