Set your Monitor res properly (as suggested above)
SSAA: off
SSLR: off
SSAO: off
MSAA: 2x (you could probably do 4x if configured properly but start with 2)
Anistropic: 16x (this barely makes a hit on GPU I find, might as well crank it)
See how the above effects your FPS to start then:
Civ. Traffic: Decide how much you like this as it can take a large hit on your CPU (call draws which could prevent your CPU from sending enough info to your GPU)
Heat Blur: Do you really want this (I never cared for it much as I'm in cockpit 99.9% of the time )
Clouds: Ultra (ooooo those do look pretty but do eff with FPS)
Then
Shadows: Like clouds, they're pretty, but can make a large hit.
If you can find enough FPS improvement in above you can probably afford to start bumping things like scenery details and forest visibilty. Personaly (in VR) I bring Forest details down as lower poly trees look almost as nice as the full poly trees.
Hope that helps.
We haven't touched on other factors like do you have any software running in the background like discord or other tray apps that are eating CPU cycles.... Lots of guides on line. DCS will take some time (as will any flight sim) to help setup properly for your rig.
We must have been replying at the same time... good catch, he said he had a 1440p monitor.
You are basically rendering wasted pixels... That alone should afford you big gains.
