Instead, it's all either slow, slow backend frameworks like Ruby, or even worse, these SPA applications that require extensive client-side JS processing before they show you the goods.
Node is a step in the right direction for both problems: for the first, Node-based backend applications are faster than Ruby and Python, and for the client-side rendering problem, because Node can pre-render these SPA apps (which everyone should do for a serious production app that uses a framework/library like AngularJS or React for major client-side rendering).
But a server application based on D or Rust, or even Go, is an even better solution to the slow backend framework issue. Unfortunately, no one has yet created a full-service framework like Rails or Django for any of those languages.
Usually this is a matter of bad coding or overprovisioning of whatever is being used to host the site and the DB. Most maintained languages running on modern hardware can sustain reasonable loads without any significant performance issues. While client-side bad-performing frameworks abound, the last I looked into it, Ruby+Rails isn't that much worse or better than any other.
Very nice.
The source code running it - https://github.com/CyberShadow/DFeed
http://forum.dlang.org/
(The forum is a front-end to the mailing lists / newsgroups.)