"Caching does not work if the data is different for everyone." I think caching can work, but at a different level of granularity. Rather than cache a person's

"Caching does not work if the data is different for everyone." I think caching can work, but at a different level of granularity. Rather than cache a person's full timeline, which is composed of multiple sub-feeds (each of which requires a database query), cache the data from the sub-feeds themselves, then recombine them on every page load. This would significantly lower the number of database queries, as each cache element would be invalidated only when its "owner" sends a tweet. This solution would be much more CPU intensive on the application servers, though, and Ruby may not be the best tool for the job if that were the case.