In my initial post I was saying:
What I’ve realized is that if you set the simulator to 60 fps it ends up rendering for example in average 55 fps (60-a). But if you set the simulator to 30 fps it won’t render to 30 fps but around 27 fps (30-b), even though it is capable of rendering at 55 fps. In other words, by the time the simulator renders the frame and by the time it displays it on the screen, there is a ‘synchronization’ point which prevents rendering fast enough to reach the maximum fps limit you’re configuring.
Any game capable of rendering at 55 fps (30+c) is definitely capable of rendering at a fixed 30 fps, instead of (30-b) but it seems it is not the case with FS2020. I’m not sure whether this is a bug in FS2020 ‘present’ logic, or a limitation because they are using DX11 or anything else, but I’m sure it is not normal.
Otherwise, if you’re ‘buffering’ the rendered frame, you also need to store them in VRAM and this adds up in 4K. These buffers which must remain allocated will prevent the simulator from loading up all the resources needed for one frame (potentially) and will therefore cause the simulator to stream vertex and texture data per-frame. Therefore I’ve chosen disabling as much buffering as possible in order to free up some useful VRAM.
The overall combination is working good for this card because it frees up enough VRAM while not loading it up too much with the balanced rendering settings, and in effect, I rarely notice the simulator needing to stream data per-frame.
In most rural and empty areas you have room to raise some of the settings if you want, and in urban dense areas fps will drop as expected but not much.
The only drawback I’ve not found a workaround yet is that if you’re for example flying and looking down the aircraft vertically in external view over autopen buildings (I test over Nice - LFMN), you can feel micro hesitations when looking at the buildings and scenery passing by beneath the aircraft. It resemble a film which is skipping a frame from time to time (think a dent in the rotating wheel skipping the film stock hole in an old movie projector). It is however barely noticeable when looking from the cockpit or down even at 75 deg angles.
This effect is most likely due to the ‘fast’ sync and my hardware trying to push up, but conversely, this might be proving these settings are the most efficient because the CPU and the GPU are pushing as much they can.
[update] This is judder and you might want read the new Monitor Settings (Freesync/G-Sync) topic in the 1st post. It you do have a compatible monitor you can eliminate judder with this!
And I thank you for sharing you feedback, it will certainly help others too!