Yep, just as I remembered - in 1169 the problem is significantly smaller. In 1173 Astalos causes the game to run at between 18-22 frames after a few seconds of encountering him. In 1169 there are still minor drops but it doesn’t dip below 25 and generally stays on 27-28 seemingly depending on whether both wings are on screen or not. Roars also do not cause any noticeable drops on 1169, 1173 has roars dropping the framerate to 20-25. Checked on the same mission in the exact same location, even tried looking in the same directions of the map. Exact same configuration on both versions, copypasted the entire user folder.
EDIT: Actually double and triple checking it seems the problem still happens in 1169 as well as 1164 but only sometimes, sometimes it runs normally. And yet I’m dead certain I’ve fought Astalos in the last few days without any framerate issues. I’ll try to test a few earlier builds just to be sure.