Apache servers

From https://wiki.apache.org/httpd/RunningMultipleApacheInstances that you linked to:

"If your virtual hosts have different requirements (e.g. mod_perl for one virtual host, mod_python for another, and maybe mod_php for a third virtual host), then your apache instance is almost surely a RAM eater. Remember that httpd will instantly spawn new child processes of the same instance as needed ... if your perl web app is being frequently accessed, why spawn several instances of an httpd process that is also loaded with mod_python, mod_php and an assortment of other modules that, at least from the standpoint of the perl web app, are useless?"

Now, spawning a child process surely eats up virtual memory, but aren't multiple copies of shared libraries are -well- shared in real memory (RAM)? So spawning a child won't eat up RAM beyond what is needed for that particular process' private data set, AFAIK.