take a look at this, from (Microsoft's) Flight Simulator forum:
The important thing to understand is any modern game will be either CPU or GPU limited with a given set of settings. Usually modern games are GPU limited, (because modern games emphasize awesome graphics and screens have got bigger). Most games are so limited by the graphics processing that it’s not possible to max out the cpu, but FS2020 is different because there’s plenty of work the cpu can do if the settings ask for that.
The OP has a 5-year-old top-end graphics card (which now counts as weak) and a weaker cpu, so here’s what he should do (other than upgrade), actually it makes sense for everyone:
Run the in-game developer FPS tool (I posted on this here separately)
The tool will tell the frame rate, whether the sim is cpu or gpu bottlenecked, and how many milliseconds per frame the ‘main’ cpu thread and the gpu are taking. E.g. if the main thread is taking 40ms per frame then your MAXIMUM fps can only be 1000/40 i.e. 25 fps. You’ll see the “limited by gpu/cpu†message is whichever of gpu or ‘main thread’ is taking the longest.
If you are CPU limited, then reducing the settings that load the CPU will improve your frame rate. These include AI aircraft, scenery LOD, and object LOD settings. So reduce these (err on the side of a big reduction first) and watch the fps and ‘main thread’ milliseconds. When these come down to the same as your gpu, your fps will be maxed.
If you are GPU limited, then reduce just about any other setting. I’d start with the graphics scaling parameter - this reduces screen resolution but does it better than simply choosing to run full-screen at a non-native resolution. Similarly monitor the “gpu milliseconds†until they match the cpu. The settings for trees and bushes are heavy on the gpu also. Also reflections IIRC.
I’m not suggesting you just dial everything down to “■■■■â€, just do the adjustments in 3 & 4 until you max your FPS at a reasonable rate (and your FPS tool will be flickering between gpu/cpu limited) and then you can carefully tweak individual settings until you get the trees (or whatever) the way you like them but understand the trade-off you’ll have to make with the clouds (or whatever).
By the way, do this with ‘custom weather few clouds’ on the runway at LOWI, so you get a repeatable test setup. That airport is pretty busy so you’ll also see the framerate hit each time a player passes in their 747.
FYI my 32GB, 9700K, 2080Ti, 4K, Ultra setup really was around 28-33fps there, and I used the method above to tweak it up to a smooth 55fps (including a serious graphics scaling of maybe 70%, I forget). The surprising thing was at 1080p/Ultra the fps was still only 42 fps because the 9700K was maxed out (and the gpu was under 50% used), hence adjustments needed for both cpu and gpu even though my rig is above the MS spec. I think MS are making the auto default settings too high and this is disappointing people.