As a follow-up to my last post, I just happened to be doing a little testing on the following proxies:
I'm pleased to say that having both of these proxies serve in front of Apache did not cause a serious impact in latency for my purposes. Why do I have a setup like this? I use Apache for complicated stuff. NGINX for handling connections, "routing", static files, and compression. Varnish for connections, routing, and caching.
I'll post more details as I collect them.