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About this mod

This mod can significantly improve the performance of Subnautica with the frame rate doubling in certain cases.

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NOTE(2020-10-27): A recent Subnautica update seems to have fixed the CPU affinity issue since I do not notice any performance improvement by disabling cores. I have updated the mod with an option under General Options to enable or disable the CPU affinity tweak just in case there are still some people who still benefit from this tweak.

NOTE: This is a work in progress and there are issues with the rendering of the water surface while underwater but the benefits were just too good to wait until all issues were fixed.

Changes in Version 1.0.3:
  • Updated to work with QModManager 4

Changes in Version 1.0.2:
  • Added an option to disable the CPU Affinity Tweak
  • Added more advanced graphics options in the graphics tab
  • Fixed the problem where objects above the water would sometimes disappear and reappear when near the surface of the water, especially when piloting the Seamoth on the surface.

Changes in Version 1.0.1:
  • Added an option under General Option to allow the selection of the number of CPU cores to use if your system has more that 4 CPU cores.

Subnautica and many other Unity based games are known to have really bad performance on systems with CPU's that have Hyperthreading or SMT. The workaround has been to only enable physical CPU cores by setting the affinity of the Subnautica process in Windows Task Manager. This mod will automatically force Subnautica to only use 3 physical CPU cores by default to boost high load performance by about 80% on some systems so you don't need to use Task Manager or other methods like Process Lasso to adjust the affinity.

Subnautica also renders(draws) base components and other objects like the Cyclops and Seamoth up to 1700m away regardless of if the player is above the water or below the water. You can only see about 200m away while underwater because of the water haze, so the mod will only render objects within this distance when the player is underwater. This can sometimes double the frame rate if you are looking in the direction of your base etc while more than 200m away.

The mod also reduces the above water render distance from 1700m to 1000m to further improve performance while above the water. The downside to reducing the render distance is that you need to get closer to things like the Aurora and islands before they appear. However, both the underwater and above water distances are configurable using sliders in the Graphics options menu so you can increase or decrease the distances to your preference. Higher distances mean lower performance.

The mod also reduces the distance at which high detail versions of objects are rendered by reducing the LOD Bias value from 10 to 1.3. This can be adjusted using the HD Distance slider in the Graphics options menu instead of having to adjust it from the F3 menu. Higher values means lower performance.

If you only want the processor affinity tweak, just put all the distance sliders the the Graphics option tab to the maximum values and enable the CPU Tweak from General options.

If your CPU has more than 4 cores there will an option under General options to select the number of cores to use, so you can experiment to find the best number for your system. After loading a save file, Press F3, then press the ~ key, type fps and hit enter to get an fps display at the top left of the screen. Go to the General options menu and select different numbers of cores to see which one gives the highest fps.

Known Issues:
  • The sky, moons etc are no longer visible while underwater until you are very near the surface when the underwater range is set to less than 100(equivalent to 1000m) You will also notice a bright halo effect of the sky being rendered only on the edges of object while looking up from underwater so if this bothers you, you can increase the underwater range to 100 but you will lose some of the performance boost until I can fix the sky problem.


1. Download and install QMods. After setting the correct location of your Subnautica installation make sure to remove the "not found" at the end of the installation path in the QMods Installer. When the installation is complete you should have a folder called QMods in your Subnautica folder.
2. Extract the PerformanceBooster folder from this zip file into the QMods folder in your Subnautica installation folder. When done correctly you should have the files mod.json andPerformanceBooster.dll in a folder called PerformanceBooster inside the QMods folder. An example path would be "D:\Games\Subnautica\QMods\PerformanceBooster"
3. Run the game and check if the mod was successfully installed. The bottom of the Graphics tab in options should now have options to adjust drawing distances.

Note: You may need to reinstall QMods each time the game is updated to re-enable all installed mods.

To remove only the Performance Booster mod, delete the PerformanceBooster folder from your QMods folder. To remove QMods just uninstall it from control panel.

If you experience any bugs with the mod installed, please let me know and if you like the mod, don't forget to endorse it to help others find it.

My other mods:
VR Enhancements
Better Sprinting
Blurred Texture Fix

Other Performance Related Mod Recommendation:
Geysers Performance Fix