Greetings -
I would like to report my experience for Simmers with outdated PCs
I fly MSFS on i6700k, gtx 1080 ti, 16 GB ram, single LG monitor g-sync compatible
In sim settings are 1080p, TAA, render scale 125%, TLOD 150, OLOD 150, everything else Ultra except traffic (I use FSLTL on lower settings)
With these settings my FPS are 40 average and Vram usage well below the 11 GB max of 1080 ti
With DX12 and g-sync enabled I have silky smooth behaviour (except on big and busy airports)
With DX11 when I get micro-stuttering in flight, more often when panning around
Hence DX12 is definitely the winner here
Happy flights!