I\'m pretty well up to speed on general web programming languages, but one of the tools I\'m working with right now is in CGI. All I can tell is that CGI scripts are quite slow.
I know of 2 projects that are being actively being developed that still use CGI scripts to good effect.
The first is Webmin a web-based system administration tool that I've been using for years.
The second is GitWeb which allows you to setup a web interface to your Git repositories.
As to the speed of CGI (or lack thereof) I can't really comment on that. From my experience with Webmin I can't say I've had any issues on that front.
CGI is protocol, it is most basic and most standard way to create dynamic pages.
There are many cases where it is useful:
So... CGI is simple but still very useful API, allowing to do stuff simply.
For example, the script that shows uptime of your server
#!/bin/bash
echo Content-Type: text/plain
echo
uptime
What can be simpler, easier and less web-server dependent?
Real time operating systems where porting (for example, PHP) is not an option.
Many shared hosts serve server side languages like PHP, python and perl through CGI