Believe it or not, the way PHP is installed on your server can greatly affect your performance!  There are two ways to install PHP on your server:

1) As an APACHE module:  This method provides the fastest operation of PHP and is generally more compatible with scripts and other server software.

2) As a CGI binary:  This method is used when security is key.  When there are several web sites on one server, this method provides better tracking of each domains use of PHP.   The price is slower PHP.

If you have your own server, you want to install PHP as an Apache module.