I can report now. I deleted affinitymask without any side effects to addon manager I experienced earlier. The stutters are gone!
Of course they are. Windows does a good job of optimizing the core allocation, and it's different for every installation so, if someone said 84 was good for him, it doesn't automatically applies to everybody.
My worry is huge FPS hog at KLAX and KJFK though. But that is tweakable in a different way.
The flickering at KIAH, remains however. I have to say you are right about runway flickering, that one is gone. But I see the terrain (grass mostly) flicker. It is like the autogen within the airport that has issues.
I can only repeat and confirm the flickering is entirely gone now.
So I can confirm leaving out affinitymask helps. But KLAX and KJFK are having tremendous lagspikes, in contrary of other airports. Will there optimization possible for those two in future live updates?
The optimization that reduced stutters at KIAH wasn't related to KIAH in any way so, it's applied to all our sceneries. And of course, I cannot see any stuttering at KLAX or KJFK. But they live in a very dense area so, if your settings are too high, it's possible the rest of the scenery around causes an fps loss.