Hello!Welcome to the forums and thank you for the feedback.
Quick question running the pack on windows 10?Can you share you PC specs for future reference?
You can control grass density from MO's toolbar shortcuts
Less (20 | 50 ) is more performance heavy while more (75 | 100 ) is more performance friendly.Grass can eat a lot of FPS when very dense.
I remember there was a mod that removed "distance fog" . Here you go.
Dyndolod can also eat in a dozen of FPS when playing at those high resolutions.To disable to go an "inside cell" go to DynDoLod MCM menu and "shutdown". Disable all Dyndolod resources and mods (don't forget billboards) and load you game.
If you have the time and patience to create a 4k Recording and post it somewhere would be nice, i always wandered how the pack would look at that res.SS are also appreciated.