For a basic CMS that does not require dynamic functionality like comments, why not write static .html files to disk? Then a high-performance, static file, web server like nginx could be used to serve the files. This would theoretically deliver the highest performance web site possible.
EDIT: “Basic CMS”, in my mind, is something a company could use for their corporate site. The content needs to change my a marketing person, but there typically is no dynamic content like comments.
Though this is not a direct answer to your question, I remembered some blog post I recently read about this, which might be of interest to you: baking vs. cooking.
It describes the conversion of a WordPress blog into a “baked” solution.