Well, as I made an account here why not share something regarding RTSS which hasn't been reported here afaik. I've made a post in MSFS-forums about this: RTSS w/ NVIDIA REFLEX (pictures included). In short, RTSS has an option in setup where user can choose the framerate limiter mode (async, front, back, reflex). We should be using the reflex-mode here with fixed-sync monitors instead of the others which cause several problems as detailed in this thread. As a result, most of the lag vanishes as it should due to reflex being in control.
All the best & take care :3