PHP integrates with the server. It does not have the spawn a new process per request like CGI

I think dreamhost runs php as fcgi.

I'm actually not sure that fcgi is that bad, even for other languages, but most shared hosts will probably limit what you can do in terms of resources.

I don't understand the distinction you're trying to make.

Not having to spawn a new process greatly decreases the time it takes to process a request, which greatly increases the amount of requests you can serve with a given amount of hardware.

The difference in resource consumption is huge.