In any thread where a youtube video is embedded, all posts after the youtube post will not load. I thought it might have been an adblocker or noscript issue, but the problem persists even with both of those turned off.
Threads do load properly when viewed in IE, however.
edit— Once the thread has gained sufficient replies to spill it over into another page, that page and all subsequent pages will load fine. It’s like the youtube video itself is causing some part of the scripting to break down on whatever page of the thread it appears.
edit 2— fixed issue by forbidding shoryuken.com scripts. hahah.
Apologies if this is a problem unique to my specific setup.