I think we'll be able to make use of some of the internal caching functions that WordPress has. Now that we have a cache dir, we can also write some file caching to even cache full html pages. This would lead to a significant performance boost.
The front page post aggregation query is also very expensive and could use some result caching.
Caching post aggregation query. Refs #42
Caching main nav. Refs #42
Caching social feeds. Refs #42
This is being worked on in the browser-caching branch.
Merged in! 7ca055c