[rshao]

Probably the easiest would be to use memcache for some of the repeated queries, specifically the items that are relatively static, such as the original post or posted item details.

It probably wouldn't help too much on the front page, since that'll update constantly and therefore just be a waste of overhead.

[boucher]

This doesn't really address the issue that there's no centralized information repository. With the content entirely in RAM, to distribute the app to two boxes would require either some sort of message broadcasting system, or re-architecting the data to be stored in some other way.