[seanp2k2]

Check out ESI blocks: https://www.varnish-cache.org/trac/wiki/ESIfeatures

Varnish will very likely be an order of magnitude or two faster than sending requests to your app. You can get going with a simple config in a few minutes and without breaking anything (just have varnish listen on a different port and use :80 or your app server as the back-end), so I'd strongly suggest playing with it if you're curious. It's pretty impressively fast software, and VCL gives you an awesome abstraction for controlling how the cache handles different routes.