I find that happens a lot. Doesn't last long, though. Usually comes right after a couple of refreshes. I also find that sometimes the pages don't load - I need to refresh them a few times before they load and / or I need to go do something else for a half hour or so and come back to the boards later.

I think it has something to do with the times that I'm accessing the boards. Probably not during peak hours so probably the times when the system stuff is doing its thing...