I found one way to avoid all stutters and landing FPS crashes:
So I too have been having the same stutters at intermittent times, and severe fps hit at landing. The only change I made in the last month was to buy a ASUS usb monitor (so I could run Skypark, Navigraph, Little Nav Map) . So based on the other thread going about issues when undocking ATC windows (I don’t do that, but they were also using a second monitor), I did a full reboot without the usb monitor on, then I ran MSFS with no mods running except the bravo lights, and did the same flight I did where I saw really bad stutters just the other day, and no stutters at all, all the way down to landing. I run MSFS at 4k full screen right now (to a samsumng 120 tv) with great fps.
So I need to try again with the mods I use added back, and after that test try with the second monitor turned on, but not clicking out of MSFS. Then if I can recreate the stutters with the second monitor turned on and going back and forth between the windows, I’ll try running MSFS windowed and see if I get the same issues.
My theory is that what I and perhaps many others are seeing is all based on running MSFS then clicking out of it during flight, ie changing focus is causing something - memory, CPU affinity, GPU loading, to suddenly drop. Will try more testing tonight.