Depends how much you push over the process boundary. The main benefit of a CGI model is guaranteed cleanup of resources, so the more you keep in the CGI side of

Depends how much you push over the process boundary. The main benefit of a CGI model is guaranteed cleanup of resources, so the more you keep in the CGI side of that boundary, the less potential you have for resource leaks, or data leaking between requests. If you just push your entire app into a long lived process you gain nothing. If you e.g. "only" use it to cache resources that are slow to obtain access to (e.g. connections to slow starting resources, data that is slow and expensive to parse), then it could be a win. But it's been years since the last time I felt that win was sufficiently worth it to design a system that way. In theory, I still love the idea of a guaranteed clean slate, but I'm not willing to give up the slow starting language runtimes I prefer today (e.g. Ruby) for the sake of it.