4.12 bad performance

its a main empty level with 70 sublevels. they are always loaded and I’m not using streaming volumes.
no I’m not using world composition.
yes I’ve read the articles before, actually I’m not having any lightmap problem. All those 70 levels build with 0 error.

the game is running perfectly fine on 4.11
I’m just reporting that the same project get really slow on 4.12

I just baked light on 4.11 and its running solid and noiseless at 99 fps.
when I had the project with baked lights (in 4.12) it was running at 40 / 60 fps and full of peaks