Getting DCS World to 75fps on a i5-4590 + GTX660 (with major caveats)

tldr; Some settings for getting more FPS out of DCS if you really want to get to 75fps and don't care about combat.

The major caveat being; you can't really play it as a combat flight sim because you can't see much to shoot at because nothing you'd want to shoot at is being rendered until you fly into it (can use better settings depending on the aircraft). If you have a more powerful computer you will be able to get away with only reducing some of the settings to see a bit more and still get to an acceptable frame rate but you still won't be able to get into any combat because smoke or an explosions kill the frame rate.

If you just want to fly around and click buttons in the cockpit you can do that. Just pretend you're playing MS flight sim. (I just wanted to be able to go through the engine start tutorials without judder when I looked around, the fact that I can fly around a bit was a bonus).

Some aircraft are worse than others. To get the Huey to 75fps I had to reduce it so that very little gets rendered. The A-10 can still have some stuff being shown. The TF-51 you can leave even more on.

I have been testing with: the instant action cold start for the TF-51 and the engine start training missions for the Huey (terrible choice as the airfield is full of stuff) and the A-10c.

Second major caveat: Just because something isn't being rendered, it probably doesn't mean you can't hit it (I can still hear things flying past when sitting on the airfield), you just won't see it until you've already hit it.

The settings I've been using are: Press the "Low" button in the graphics options. Then turn textures up to "High" so that the cockpit text is readable if you lean in. (http://i.imgur.com/XBl2Du3.jpg)

Then I've been using some pretty drastic view range reductions in the graphics cfg file. You'll have to make one of these to put the settings in. It's just a standard text file (UTF-8 encoded, use Notepad++ if you don't know how to check the format your text editor saves in). The file is C:\Users\YOUR_WINDOWS_ACCOUNT_NAME\Saved Games\DCS\Config\autoexec.cfg The file just overrides graphics settings.

The contents of that file when using the Huey was:

options.graphics.Camera.Low.lodMult = 0.3
options.graphics.Camera.Low.structures  = {2, 100}
options.graphics.Camera.Low.trees = {1, 5}
options.graphics.Camera.Low.dynamic = {1, 100}
options.graphics.Camera.Low.dynamic2 = {1, 100,0.5}
options.graphics.Camera.Low.objects = {2, 150}
options.graphics.Camera.Low.mirage = {1, 1}
options.graphics.Camera.Low.surface = {25, 250}
options.graphics.Camera.Low.lights = {5, 500}
options.graphics.Camera.Low.districtobjects = {1, 10}
options.graphics.Camera.Low.districts = {1, 10}

For the A-10 the settings were a bit less drastic, but it's going to depend on what you're trying to do. Realistically a 660 is too old to expect much of in DCS with a HMD.

options.graphics.Camera.Low.lodMult = 0.3
options.graphics.Camera.Low.objects = {50, 750}
options.graphics.Camera.Low.dynamic = {25, 00}
options.graphics.Camera.Low.lights = {50, 5000}
options.graphics.Camera.Low.districtobjects = {10, 10}
options.graphics.Camera.Low.districts = {200, 200}

If you really don't want to render anything until you hit it then (if you can't hit 75 fps like this you probably aren't ever going to hit it):

options.graphics.Camera.Low.lodMult = 0.3
options.graphics.Camera.Low.structures  = {1, 2}
options.graphics.Camera.Low.trees = {1, 2}
options.graphics.Camera.Low.dynamic = {1, 2}~~~~
options.graphics.Camera.Low.dynamic2 = {1, 2,0.5}
options.graphics.Camera.Low.objects = {2, 5}
options.graphics.Camera.Low.mirage = {1, 2}
options.graphics.Camera.Low.surface = {1, 2}
options.graphics.Camera.Low.lights = {1, 2}
options.graphics.Camera.Low.districtobjects = {1, 2}
options.graphics.Camera.Low.districts = {1, 2}

If you can't get to 75 but can manage 60 then go into the nvidia control panel and set the rift to 60HZ. That took the judder away for me when I was only managing to get a fairly steady 60.

I'm still not exactly sure what the various graphics settings mean. My current guess is that the value pairs (at least for objects and dynamic things) are "Max number rendered" and "Max distance away to render at (in meters?)". Object, Dynamic and the lodMulti made the biggest difference to my fps. All the default values can be found in YOUR_DCS_FOLDER_PATH\DCSWorld\Config\graphics.lua. You can also see the differences between low/medium and high in there, it may help if you do have a better system and want to try and find a middle ground between low and "so low it's almost nothing".

Still using 0.4.4 runtime. Rift set as primary monitor with desktop in extended mode.