What is the “CGI Overhead”, and should I be worried about it?
The CGI Overhead is a consequence of HTTP being a stateless protocol. This means that a CGI process must be initialised for every “hit” from a browser. In the first instance, this usually means the server forking a new process. This in itself is a modest overhead, but it can become important on a heavily-used server if the number of processes grows to problem levels. In the second place, the CGI program must initialise. In the case of a compiled language such as C or C++ this is negligible, but there is a small penalty to pay for scripting languages such as Perl. Thirdly, CGI is often used as ‘glue’ to a backend program, such as a database, which may take some considerable time to initialise. This represents a major overhead, which must be avoided in any serious application. The most usual solution is for the backend program to run as a separate server doing most of the work, while the actual CGI simply carries messages. Fourthly, some CGI scripts are just plain inefficient, and may ta
