I would say performance is generally poor. The rendering of pages seemed plenty fast, but downloading of all the content/css/js was painful.

Some quick things that would help:

* use :cache => true for both your CSS and JS files, this helps more than you'd guess

* make sure passenger is serving your static content without hitting the rails stack. I don't know much about passenger, but you should check on this.

* as 'there' said, use properly resized thumbnails.