Install this: https://github.com/fholger/vrperfkit/releases , then I am attaching my config (I also use a 3080). Replace the default one from the zip with mine. Set oculus resolution slider all the way to the right (yes you are reading that right, maximum res) then play around with the renderScale value, I use 1 to 0.95 in single player 0.95-0.85 in multiplayer and 0.80 in demanding multiplayer servers but you need to find values that will give you optimal headroom.
EDIT: (note you need to restart DCS for the change to take effect). If you still won't be happy with the results, change the refresh rate in Oculus to 90 or 120hz and lock your DCS framerate in Nvidia control panel to 60 or less if you can stand it.
vrperfkit.yml