The site has had a few issues like this since a couple of days after the conversion. At one point I couldn;t access it at all.
It's not the the pages take a long time to load, but rather the site takes a long time to answer your request.
I was just about to ask the same question - I click on a topic and then go make a cup of coffee while it loads. I have broadband and most other sites load lots quicker. Never used to be like this..... (Can I have some cheese with this whine? ;-) )