Adam, you are totally right that the 304 mechanism may be working. The point is, that the resources are returned with a Expires header that is set to Last-modified. That means the Expires date is always in the past. Thus the browser immediately expires the resource and does not even try to use a If-Modified-Since. Therefor a slight improvement would be leaving the "Expires" headers away. It would be even better if Expires would be set to "request-time + some hours". Alternatively just a Cache-control max-age header. Cheers! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4143890#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...