My issues, as I’ve outlined in my thread over here, are similar to @Orishek and @PunchDkns99
I uninstalled ALL handmade airports and world updates, and still have a 5-10FPS delta between photogrammetry on and off (both in and outside of photogrammetry areas). It is a CPU threading issue when photogrammetry is enabled, I believe (I also tested this with ReSize BAR on and off, and with SMT/Hyperthreading on and off; same result all around).
I also tested this on my home-office PC, which has a fresh copy of W10 and a fresh copy of FS2020 on it, with the same results.
It’s clear that there’s room for improvement in the DX11 version of FS2020. I’ll refrain from judgement until we all see if anything has improved in the SU8 beta, whenever Asobo decide to allow the public to test SU8.