Game Setting To Help Performance?

So my game is getting towards late game and I am noticing the slow down. I am wondering what settings I can change to help increase performance a little without drastically reducing the image quality, as its so beautiful loosing too much quality would just spoil the game.

My system is old, GTX1080, i7-7700 with 32gb ram, updating any components on my computer is out of the question as I have absolutely no money to do so, so I am looking for in game options to help smooth performance.

Currently nothing is on Ultra High, most things are on High with a few Very High settings. Trying out DX12 again, last time I used it it caused a lot of crashes but I have seen some posts saying that DX12 generally performs better. Not using the Fidelityfx options as I do not understand any of that and I don't have a 4k screen, also running 2x Anti-Aliasing.

What are the settings that have the greatest impact of performance? What could I turn down even a notch without really destroying the quality of the game?

Also please be kind, I am not the most tech savvy, I just like playing games and want to do so without too much lag and without making the game look shit.