Apache MPM-Prefork launches a new process for each connection. It is as inefficient as it sounds, But unfortunately completely normal.
I never run apache with MPM-Prefork, It is the default for ease of administration.
Apache has two other MPM's available, MPM-Worker and MPM-Event.
Worker is multi-threaded and Event is asynchronous.
I prefer Worker, as it is more mature and IMO still offers better performance.
Some prefer Event, and say otherwise. Either way better then forking a process every time.
PHP is by default non-thread safe, some would say no matter what non-thread safe! So you can't use regular mod_php with anything other then MPM-Prefork.
You can however use MPM-Worker and serve PHP with FastCGI. I prefer doing FastCGI via PHP-FPM, however with Cpanel it's very easy to do it via mod_fcgi.
You should recompile apache with the easyapache script.
Update your Cpanel before running easyapache.
make sure to choose
apache 2.2, PHP 5, MPM-Worker, FastCGI, suEXEC
I also choose Suhosin for security, and eaccelerator / Zend optimizer
once the build is done, you will get a menu to choose how to serve php, chose fcgi!
read more here
...Or deal with crappy performance.