This is the first time I've ever had SweetFX make my performance worse, which sucks because it makes this game look so much better.
Post sweetfx_settings.txt in a spoiler tag and I can tell you what's turned on that probably shouldn't be. The one I'm using now is Lumasharpen, Levels, Tonemap, Vibrance, Curves, and Dither, and it has no noticeable FPS hit.
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Semi-related, for visual enhancement that also improves FPS over vanilla, the best setup I've found so far is:
Optimized Vanilla Textures
Vivid Fallout - Landscapes
Vivid Fallout - Rocks
FAR - Faraway Area Reform
Darker Nights (no darker than Medium, because of the next mod below -- I use Light/Vanilla/Vanilla/Vanilla.)
Realistic Lights (indoor/outdoor & also note that this mod kind of looks like ass in the screenshots, but try it anyway because it really does improve the game's lighting, especially indoors)
Ceano's SweetFX - RL (edited to remove SMAA and tone down lumasharpen because they fuck up the game's text horribly, and remove Bloom because bloom is garbage and it has a pretty significant performance hit too)
FPS dynamic shadows - Shadow Boost (this mod dynamically adjusts your shadow rendering distance based on current frame rate, makes a big difference in downtown areas)
Tried both of the mods that add shadows to pip-boy light and headlamps, and deleted them immediately because the game engine is broken and does not render those shadows correctly. No idea why they are popular or how anyone can stand to look at shadows that look like a ghost hovering behind characters instead of an actual shadow on floors, walls, etc.
I also type "cl off" into the console every time I start the game now. Don't know of any way to do this in a mod at the moment, short of using ENBoost which is a big NOPE.
energy resist is not a means to detect afaik. they can have energy resist from gear they wear.
That rumor got started because Green Rag Hat has 10 energy resist as an Item Effect instead of as a normal armor stat. No idea why, there's no reason to do it that way. Regardless, it's not immediately obvious that the character has 10 ER because of that and some dude just happened to find a synth wearing that item and was fooled by it, and it snowballed on reddit from there.
There's no way to use VATS/Awareness to find synth spies in your settlements.