I still use CGI in most of my web apps, some of them SaaS applications, and them performs pretty well.

The author mentions CGI overhead. Well, that's relative, please read this: http://z505.com/cgi-bin/qkcont/qkcont.cgi?p=Myths%20About%20...

One important side effect of CGI is the fact that if one route crashes (in a REST api for example) the CGI finishes its execution and nobody is harmed. On the other side, with server daemons, one bug can kill the whole app.