Just in case, here's a tutorial for fixing choppy water/bad terrain: https://modthesims.info/t/479610

Is your "smooth edges" setting greyed out ingame (in the graphic settings accessible from ingame)? Just curious, because that's the game's AA, and being greyed out means the game isn't properly reading the graphic card/chip. With your specs I don't see why the game should lag so badly, or look bad, unless it's trying to run on an integrated chip. It's often an issue for laptops with dual graphics.
Manual edit for smooth edges (scroll down) - https://simscommunity.info/2016/04/...es-sim-shadows/
Another tutorial here with a bit of extra info: https://simlili.tumblr.com/post/146373494212

If changes made with the GRM don't seem to go through properly, and your game is installed in Program files, Windows could be an annoying piece in this. It's not certain the GraphicRules file is saving properly directly from GRM. Try saving a copy of the edited file to your desktop (directly from GRM, after editing it), then manually replace it. If you do notice the changes, it's likely fine.

You may also want to use the 4GB patch (helps with lag/crashing) if you don't already use it. I think the RPC is pre-patched.

If you've used Reshade, that's the only reason I can see how the game would be blurry (not counting AA). Unless you've got the texture detail and sim/object detail on low settings ingame. You'll want to check if anything is set to low, missing, or greyed out in the settings, like with smooth edges (means GR settings likely need some editing still).