GeForce Experience present and with auto optimisation on? Found that GeForce Experience could reconfigure settings after Forza has, meaning Forza then tries to go back to what it wants and GFE swaps everything back to a higher level that’s just that little too much for the card after the graphics update that came with the update released right before the rally expansion. The interference can possibly set DRM going nuts, and, believe it or not, sometimes turning the graphics UP if something has set them to 1080p and Low/Medium to 4k and “High” can make it run as smooth as silk.
The DO NOT update lag issues were pretty solved, but the “upgrades” that came for the rally expansion have caused chaos. Sometimes if you were running “Ultra”, the upgrade was too much for the GPU. Sometimes it set things too low and caused even more chaos because the graphics card tried to do more than the game would allow.
No idea if the latest game update will make a difference to any of you.