In reply to Ryan Hellyer.

In other words, batcache is the only plugin that has a good answer to the cache invalidation question. For the other plugins you need to erase the cache files which might be an expensive disk operation.

Another very nice feature of batchache is that it tries (or tried? haven't looked at its code for a while) to cache things only if there is an actual traffic surge to the specific post, and don't waste your diskio for post that are being accessed only once in an hour. BTW I think that nginx can be configured to do the same but I don't trust my own memory here.