The majority of pages of one of my sites can only be accessed by registered users. While these pages do share some common, static content (headers, etc) most of the information on the page is populated specifically for that user using a variety of usermeta, postmeta and custom table data.
Further, a user is unlikely to hit the same page a lot of times. However, there are tens of thousands of users who may wish to be accessing their own information pages simultaneously, so performance is of great concern.
My understanding of cacheing plugins is that they do a great job with relatively static content, such as blog entries or "about us" pages, that change infrequently but must be served up (without any differences or customized info) to a lot of simultaneous requests. In my situation, the real performance "hit" comes once a user has logged in and is accessing their personal information.
How effective are cacheing plugins in this scenario? Are there any other alternatives (in addition to DB optimization) that can help reduce memory and DB load?