I hope I'm not stepping on any site admin toes in saying this, but the site uses a pretty well-known and tested forum software package based on php/mysql which is absolutely a robust platform. I haven't seen any problems except for the maintenance which is sometimes necessary with that combination.

There is also a bit of javascript with a widely used library, which can sometimes have complications with respect to browsers. And some ad serving of course. This really points to your browser as the main culprit. Or your firewall. You might try some ad-blocking extensions for just a test (you know, the site doubtless appreciates revenue from the ads). I use Google Chrome with no issues.