I never thought this was even possible
I have tried installing and using ENBseries a few times.
Always ended the same way.
I would have a slide show at 10-15 FPS, and start turning off effects until I reached a point I wasn't getting that much eye candy for the 15-20 FPS drop.
Uninstall and go back to muddy vanilla graphics. :(
Recently i created a couple of reshade presets to add some vibrancy and detail to my game. They only ate about 0-3FPS and worked good with minimal effort to install.
But.................. I am a graphics junkie, and wanted more.
When I saw that Rudy ENB was using Marty McFly's DoF shader which is also available on reshade.me I figured i would try again with ENBSeries.
The first thing I learned is probably most people's issue with installing an ENB, and the reason for the big frame rate hit since although the shaders add up they aren't 100% to blame for bad framerate.
There is basically 3 steps to the image now with ENB installed.
Driver -> Game engine -> ENB post process shaders.
Some things can be done at any step like AA for example.
All three can do some form of AA and each takes some processing power to do (Framerate).
MAKE SURE YOU AREN'T DOUBLING UP!
That was my main issue.
I had the game engine and ENB both trying to do AA in effect taking twice the amount of framerate to do the same thing.
Once i stripped the driver to minimal settings and the game engine to only TAA the ENB was free to use those frames to apply its post process shaders for those effects.
The other two things I learned is Shadows can kill your game.
More specifically LARGE shadow files.
The game engine by default on ultra settings is using 4096 as it's size for for shadow textures.
Now when you think about available VRAM and how many shadows are actually in scene at any given time then compound this by realizing shadows in real life rarely have sharp edges lowering the shadowmap resolution is a no brainer for more FPS.
I actually dropped my to 512 and still have good detail on things like detail shadows under the ground cover leaves giving them depth. The cloud shadows were never sharp edged so no difference there, and trees and items only a minimal difference I don't even notice during play.
Remember 4096x4096 is 4 times bigger than 2048x2048 and not only takes 4 times as much space in VRAM but also renders that much slower.
Last consideration (observation) on texture size.
The game engine applies a blur filter. mainly to smooth things out and avoid flicker in textures when looking around.
I noticed this playing with sharpening filters in reshade. I could get insane detail but would have to apply a slight blur (losing some of that detail) to keep the texture from flickering when you look around.
That's why it's hard for me to see the difference between 4K and 2K in game. I can't get close enough to the object while playing to be any difference to me.
Enough about that. Just know the larger the texture the more space in VRAM it takes and the longer it takes to render.
This next tweak I found on reddit for SSAO_SSIL in the ENBseries .ini
AO looks great and adds a ton of depth to the rendered image but the cost is pretty high.
This reduces it's cost in the ENB to 3-4 FPS from 8-12.
ResolutionScale=0.3
SourceTexturesScale=0.3
Again this deals with the size of the texture. Lower it's size and you lower it's framerate hit with only minimal difference in image after the blur filter has been applied.
Lastly I noticed my VRAM usage while playing was 5.9GB of the 6GB my card has available (I run Pfuschers Skyrim 2020, Folkvangr grass, Origins of forest, plus many other high res mods).
My texture folder was 39GB by itself.
So I ran cathedral assets optimizer and changed my entire texture folder to 2K maximum.
This changed game play VRAM usage from 5.9GB to 3.8GB, and eliminated the stutter during load since the VRAM now had overhead instead of bottoming out.
Been a fun journey, and Honestly amazed I can get these types of graphics on a 1060 GTX
Hope this helps someone who like me has tried ENB but could never get it to run at a playable framerate.
Nico