I have tested my pages in Firefox & IE and looking at Firebug in Firefox for some reason some images are taking a long time to load. They are not very big in comparison to the ones which are loading quicker.
Attached is a screenshot of Firebug.
I especially notice it in IE with the progress bar at the bottom of the page, it just sits there saying loading image…
Could it be the path or something which is http://localhost:49211/Content/_layout/images/bg-footer.png for example
I guess you are running the site in VS (using Cassini) this is really slow, I had the same issue. I used Chrome, as it shows when the browser makes a requests to the images and file, which showed a large delay on Cassini delivering them.
if this is a case, try putting you site on the local IIS (if you have an instance). the site should run a lot faster.