Subnautica 2 Performance Mod v1.0

                    
Subnautica 2 can run hard on modest hardware, especially when heavier effects like Lumen, shadows, and other expensive rendering features stay enabled. The Performance Mod replaces the game’s default configuration with custom Engine.ini presets that cut those costs and raise FPS. Furthermore, the mod offers four distinct presets so you can decide how far you want to push visual reduction in exchange for smoother gameplay. Consequently, you can match the config to your hardware instead of forcing the game to run with settings it clearly struggles to sustain.
Preset Options

Balanced Performance : recommended preset, keeps most visuals intact while trimming expensive lighting and shadow features.
Performance : higher FPS than Balanced, with more aggressive visual cuts and disabled shadows.
Ultra Performance : removes almost all visual effects for the highest possible FPS boost.
Potato PC : strips out nearly all visual effects and serves as the most extreme fallback option.

Why You Need This Mod
This mod helps if you want Subnautica 2 to feel responsive on lower-end or older hardware without waiting for a future optimization patch. It also gives you a quick way to balance image quality against frame rate by choosing a preset that matches your system. Additionally, because the presets are plain config files, you can switch between them without changing the rest of your game setup.
How to Get Started

Download the preset you want and extract the archive to your PC.
Open your Subnautica 2 config folder:
%LOCALAPPDATA%\Subnautica2\Saved\Config\Windows\

Copy the preset’s Engine.ini file into that folder.
If a GameUserSettings.ini file already exists and the mod does not apply correctly, delete that file first, then add the new Engine.ini.
Right-click Engine.ini, open Properties, and enable Read-only.
Launch Subnautica 2 and recheck your graphics settings, since deleting GameUserSettings.ini resets them to default.
To uninstall, delete the added Engine.ini from the config folder and remove the read-only lock if you no longer need it.

Good to Know

The file must stay in %LOCALAPPDATA%\Subnautica2\Saved\Config\Windows\, not in the Steam install directory.
Make sure the file name is exactly Engine.ini and not Engine.ini.txt.
The mod also works on Linux through Steam Proton. On Proton, place the file in the corresponding Windows prefix under compatdata/1962700/pfx/drive_c/users/steamuser/AppData/Local/Subnautica2/Saved/Config/Windows.
All presets disable Lumen, so interior lighting may feel weaker than vanilla. Add extra lights if your base looks too dark.