Thanks for all the effort you've put in. I'll try with the mod back on but lowering the settings a bit :)
After 20+ hours of testing using the Special K frametime graph, I found as close to perfect as possible to make the game smooth as silk, especially for people with GSYNC monitors/TVs. This is with the extended LOD mod without the extended grass.
1) Download Special K and Flawless Widescreen
2) For the Elden Ring .ini in Special K, change GameOutput=true to GameOutput=false
Another player with same results:
www.reddit.com
3) Launch the game without Flawless Widescreen enabled but with Special K enabled and the game in borderless mode
4) In Special K settings change "unlocked framerate" to "normal" while the game is running
5) Alt-tab to Flawless Widescreen and enable it with removing 60hz refresh rate and place frame limit to a few frames below your monitor's refresh rate
6) Alt-tab back to Eldren Ring and ensure that Vsync is FORCED OFF as option under top menu "display" drop-down (this should be the default)
7) DO NOT ENABLE PS BUTTON OPTION IN SPECIAL K. It causes weird frame drops and stuttering (took hours to isolate this)
Ideal Elden Ring settings would be high as the starting point.
Change grass to medium to help fps, especially in Liurnia. I also put effects to medium to help with fps drops on spells and mists (there is very minor visual loss here; mainly in distant light rendering; increase to maximum if okay with some spells/mists further tanking fps in a few places). I bump shadows, lighting, and volumetric to maximum.
With these changes, I played the game so smoothly. The random 1% frame drops that were happening disappeared and now rarely occur. When they do, they are repeatable in the open world instead of random like before.
The game is running better than it ever has for me.
Hopefully this helps some people.