It's actually rather easy: http://www.linuxjournal.com/content/embedding-file-executabl...
HTML isn't that big, so if you used linked resources, it would be pretty simple to make a C program and compile it to a binary for any purely "static" site.
But like you say, I have to wonder if it actually makes a difference performance-wise. The kernel will cache the static file data anyways. The only improvement I can see is maybe to avoid having to look up file metadata (length and mtime)? Or to avoid a syscall?