Hello, all. I've just gotten into Concelhaut's apprentice chambers (I assume that's what they are) and fought Sabel in her room. Upon killing her, the framerate dropped to a complete crawl, and then a halt.
I waited, and it seemed that at every 2 minute interval the game would briefly manage 2 seconds per frame for around 10 seconds, updating the combat log. Thankfully it seemed to provide an answer as to what the culprit was: Sabel, despite being dead, was rapidly affecting everybody with Arkemyr's Wondrous Torment.
I waited around 20 minutes for the game to unfreeze, but no luck. The combat log often looked like this:
168: Miss 90: Graze 120:Hit 320: Crit. (A rough example)
This happened multiple times over the 20 minute waiting period. Unfortunately no method of taking screenshots was available to me. I'm sorry I can't be of more help, but my PC was dying while this was happening, and it took me roughly 5 minutes just to shut the game down in task manager.
Thanks in advance.