Heavy lag when Hircine gets near

This is part of a quest; the save has met the conditions to start the fight. Just enter the cave ahead and let Hircine comes and see the FPS dropping. F3 shows high spikes on the GPU side with intermittent freezes.

I loaded the vanilla engine and didn’t found the same lag.

Instructions to test without the save:

1. Type:
   1. coc "Sinsidon Cave"
   2. Journal A_IV_Kleriker" 105
2. Kill the monsters with the console until found Hircine.
3. Look Hircine coming and the lag rising.

Linux Mint 20.2 Cinnamon 0.46.0+git202108261506~ubuntu20.04.1

Hircine_Fight_lags_a_lot.omwsave.7z