What about a native files caching system ?
I started a little snippet available here : https://github.com/mbcreation/CacheMachine so that every not connected user issuing a GET request receive an html file instead of a WordPress response.
Most of the job is done by the .htaccess behaviour and one php script in front of everything.
Then the "hook power" can handle "generation" and "regenaration" of the cached files.
What do you think ?