i'm not a fan of php and mod_perl running in the same apache instance
my setup right now uses lighttpd as a frontend proxy + static file server on port 80.
anything mp related is proxypassed to a mp2 bound to localhost on port 8000 anything php related is proxypassed to a lighttpd server bound to localhost on port 8100 that calls processes php as a cgi though fcgi --even though its a phpcgi, the speed is comparable to apache and mod_python because lighttpd has way less overhead
the only caveat on this setup, is that you can't run mod_security to filter the php stuff on lighttpd (unless you run apache as the frontend -- but its not as good at proxying or serving static files as lighttpd).
i've been trying to tweak this setup for speed and security - apache is built to handle things right, lighttpd is built to handle things fast.
