Does it really use any more RAM with python or PHP embedded than Apache + out of process Python or PHP would together? Seems to me that the main inefficiency is that the memory overhea for the scripting language is incurred whether or not there is active execution. So, that RAM is still tied up when sending a static file to a client, or when sending the buffered result of a static page. Seems like having an event-driven piece that took over for each prefork process when it came to returning the result and any logging that happens after the result has been sent would be a relatively small amendment to the architecture with a big payoff.

I know people are reverse proxying to Apache with nginx or similar for similar reasons.