My system is an i5-8400 (non-k) and MSI 6600XT OC graphics, running Windows 10. In Microsoft Flight Simulator, turning on FSR 2.0 causes the game to go from seeing the 8 GB physical VRAM to seeing less than 7 GB physical. It also starts to overrun the memory to around 9 GB, causing severe performance loss. The only way to fix it is to first switch back to another anti-alias mode like TAA, then close and restart the game. You can see more details where another user and I have filed official bug reports on the MSFS forums months ago, but even there it seems this is an exceedingly rare bug and no one has had any insight.
https://forums.flightsimulator.com/t/massive-performance-loss-with-amd-fsr2-su11/555483
I have been searching high and low on the web, and can't find any help as to why this is happening. So far I have done a clean re-install of both the game and graphics drivers, and everything is current. It's the only FSR compatible game I have, so I unfortunately can't test to see if this is game specific.
