Any ideas? Never had this problem before.
It looks like your site is doing a lot of processing when displaying a page.
have you tried adding a caching mechanism?
you can give plugin a try: http://wordpress.org/extend/plugins/w3-total-cache/
That would be the page being rendered serverside and what not. Every site does it, but since your site is on a (relatively) dark background, it's more pronounced...it sucks on black sites. You can probably minimize that with some sort of caching...but oyu're just gonna have to play around with it.