So… I reinstalled windows11 on my (old) SATA SSD I had lying around. Took about an hour, then reinstalled MSFS and had it find the files I had on my “gaming” M.2 SSD. The sims starts up in about 2min30sec, and from what I could test is quite a bit smoother too when it comes to fps and especially stutters. This is on the latest win11 version btw!
Will need to do a bit more testing, so now I can boot between my ‘old’ windows11 version and the new one (which is on a pretty small, slow SSD).
Gonna boot into my old setup now just to compare. That one is still on the old win11 version (H21 I think)
edit: just tried it on my previous win11 installation. takes WAY too long. so definitely something that got broken in my windows setup. Guess I’ll need to reinstall win11 over my old M.2 ssd installation now.