Thanks to the release of the new AMD drivers for graphic cards with RSR radeon Super resolution i just tested in dcs.
i had an average 66 fps with a 3700x at 4,2ghz and a 6700 on native resolution 3440x1440.
Now with an upscale from 2560x1080 to 3440x1440 i've got 100 fps and no problem with image quality. Nice!