The Hun's correct. PHP is slower than C/C++, uses more server resources etc, but it's a shitload faster to get stuff done using PHP.
After all, if you only care about speed you'd be using Tux as your webserver with all static content
Memories cheap, and time is too short to worry about coding your CGI app / Apache module from scratch, just do it in PHP and have time left to do the fun things in life, like eat and sleep