I don't even have this problem on Tom's Hardware forums, which is using very outdated software and is soon converting over to XenForo. They also unlike you have a Forum Feedback thread that is well staffed and responded to. Here I can't even post a thread in Technical support unless I pick a PC or console platform.

Granted, I use a VPN and Chrome Incognito mode, but again, this does not cause problems with other forums. Often times I get a big Ubi Forums not responding page, yet if I exit and relaunch my GRW Wildlands Gen Discussion bookmark, it suddenly shows as it should. Post submitting is still horridly slow though.

It's not a lack of Chrome being updated, as I have the latest version. It's obviously not cookie clutter, as Incognito mode stores no cookies. I can only conclude that your forum software is far more antiquated even than what Tom's is currently using.