WP Super Cache is a good starting point. Taken alone is not enough though. Most web shared hosting where custom wp are configured use Apache which doesn't solv

WP Super Cache is a good starting point. Taken alone is not enough though. Most web shared hosting where custom wp are configured use Apache which doesn't solve the problem because apache (2.2, the 2.4 version should have improved a bit) spawns processes containing the PHP modules, therefore using more ram than it actually needs to process an html page. This issue is vastly solved if you have a Nginx webserver with a good configuration. You can also improve that if you use memcached and the nginx memcached_pass, which directly outputs the memcached cached html without passing through php, giving a super-boost to response times. (to use this feature, checkout the WP-FFPC plugin) If one page ends up on reddit/hackernews/producthunt homepage, a system designed like this should support the bump with relatively small issue. Obviously if many people start commenting you will still have performance issue because that's when the php part is called (and that's the most memory expensive).