This is my experience with the site taking time to load:
I have noticed the be friendly links on the left in the side bar to cause some issues for me. There are times I have to wait on those to load for the forum to finish loading. Since they rely on java scripts running offsite .. the forums are at the mercy of whether or not those offsite servers are running properly or are having connectivity issues... (FB, Twitter and Google +1 causes havoc with some of my clients websites on occasion where I have put in the social media buttons. ) I tend to watch the notification bar at the bottom left and it usually say who the culprit is of the social media links.
Other times it's a ISP issue ... ( Comcast specifically for me proves to be challenging where I live. )
Then finally, other times I just get a website not available page from my browser. When I get that I check to be sure other sites come up for me. If they do come up then I know it is specifically the forum server that is having issues either with itself or connectivity.