WOW - a long time ago I ran into Apache problems (totally forgotten until I read your post.) I reinstalled and waaaay too many later tweaks from a helper finally got things going smooth again.
It's very impressive that an 'out-of-the-box' nginx installation brought such success. Maybe strategic configuration tweaks will help... but I found them often tricky.
Nginx and Lighttpd are probably the two best-known asynchronous servers and Apache is undoubtedly the best known process-based server. [...] The main advantage of the asynchronous approach is scalability. In a process-based server, each simultaneous connection requires a thread which incurs significant overhead. An asynchronous server, on the other hand, is event-driven and handles requests in a single (or at least, very few) threads.
While a process-based server can often perform on par with an asynchronous server under light loads, under heavier loads they usually consume far too much RAM which significantly degrades performance. Also, they degrade much faster on less powerful hardware or in a resource-restricted environment such as a VPS.
That, I believe, was the big gotchya. The front-end is running under a VPS-- Virtual Private Server. I think it just hit a point where the election-fueled load overwhelmed the code path in Linux-VServer and grinded to a halt at the kernel level.
As for ease, yes, frighteningly easy. Apache was kind of a hack, using it to reverse proxy the heavy backend services--when Apache is primarily a web server-- to make it fill this role took quite a bit of configuration. And it's just messy as the quote illustrates. nginx is mostly a reverse proxy, it's designed primarily for what we need, an interface to several heavy backend web services, passive load balancing, and light static serving. I haven't even read the documentation, just copy-pasta FAQ examples and tweaked for our specific configuration. Now time to hit the books!