I'm a Windows IIS developer with experience developing web applications as both cgi executables and as ISAPI extensions in C++. I am thinking of developing apps for Apache and would like to know if Apache offers the ability to create web applications as Apache extensions. The CPU efficiency of an extension is vastly superior to an application using the cgi executable model. The reason is that an extension is started only once and handles all incoming http requests. Alternatively, a web application using the Windows cgi model will start a new process for each http request and this is expensive in terms of CPU usage. I've read a little bit on FastCGI and apparently, it allows for a single exe instance to handle multiple incoming http requests. This is interesting to me, but if it is possible to get right down to the metal, I'd really prefer to develop my applications as extensions to Apache. Any advice would be appreciated.