[crazygringo]

Yup. A database gives you all the performance AND flexibility you need. MySQL or PostgreSQL will work well too.

Storing pages as files is a no-go because it wastes way too much disk space due to block sizes. While more customized cache tools will never be as flexible or have as much tooling as a widely supported relational database.

For even better compression use a preset dictionary as well tuned to a wide sample of HTML, but it doesn't sound like you need to go that far.