Forum threads caching very strangely

As of today, I'm getting a really weird and intensely persistent caching issue. If I open a thread and come back to it later, I'll only be able to see the new posts by doing a hard refresh. This is fairly normal, but it gets weirder: sometimes if I come back to a thread with new posts in it, on the first load, it'll actually load FEWER posts than the first time I visited it. Then I do a hard refresh, and it shows the thread as I first saw it. Then I do ANOTHER hard refresh, and I finally see the new posts.

I'm on Firefox 50.0.2 in OSX El Capitan.

@kcin: Can you link me to any forum threads where this is happening specifically?

@rorie It happened on a few threads, but this thread is the only one I remember it definitely happening on today. First, I visited the thread when it was 5 or 6 posts deep. Then when I came back 30 minutes later, first it loaded the OP and the 2nd post only, then I refreshed and got the posts that I had seen 30 minutes ago, then I refreshed again and got all the posts.

http://www.giantbomb.com/forums/general-discussion-30/other-great-video-game-podcasts-1804805/