The last few days, I have been having extremely bad frame drops during this boss.

Happens around when there are several blue puddles.
I usually sit somewhere around 40-60 on every other part of the game. I only see these drops on this boss.

My framerate drops to somewhere in the 2-5 fps range.

I never used to have this issue, nothing in my settings have been changed, nothing in my PC has been changed.

Has anyone else been experiencing this recently?