Enabling IINACT causes massive FPS drop

[spectria-limina]

I'm normally getting somewhere between 40-75 FPS depending on what's going on in the environment. For instance, standing in the Tuliyollal market, I get 49 FPS.

However, after enabling IINACT, I only get 20-40 FPS. Standing in the market, not having moved, I'm down to 37.

Disabling IINACT doesn't help; I have to reboot the game to fix it.

I think this is a regression? but not 100% sure, as I had other graphics driver issues limiting my FPS for a while.