How to improve FPS in Subnautica (PC)
Eight years after launch, Subnautica remains one of the most demanding underwater exploration games relative to what it shows on screen. Its Unity engine generates the world via voxels and procedural terrain streaming, meaning much of the heavy lifting happens on the CPU, not the GPU. This causes the characteristic microcuts when entering new biomes or diving quickly toward deep zones, especially if the game is installed on a mechanical HDD. Despite its relatively simple graphics, it suffers from known memory leaks that degrade performance in long sessions. With the right settings and some patience with memory management, it's perfectly playable at stable FPS even on modest hardware.
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Calculations based on our FPS model combined with the % gain of each setting (measured in public benchmarks).
1. Quick wins (no visual loss)
Start here. Each one adds a little, but together they give +50% free FPS.
Reflection Quality
Subnautica's water constantly calculates real-time reflections, and it's one of the most expensive parts of underwater rendering. Lowering it to Low is barely noticeable while swimming because the water's own distortion masks the detail loss. On the surface the visual impact is somewhat bigger, but still acceptable.
Vsync
The game's built-in V-Sync adds noticeable input lag and caps the framerate below what the GPU could deliver, especially annoying in combat against creatures or when dodging Reapers. Disabling it and using panel-level V-Sync (G-Sync/FreeSync) or an external FPS limiter gives much finer control.
Anti-Aliasing
Subnautica's TAA is reasonably efficient and helps smooth out the characteristic noise of underwater vegetation and coral without wrecking performance. Switching to a lighter mode than high MSAA frees up FPS with minimal sharpness loss, especially at 1440p and 4K.
Shadow Quality
Dynamic shadows from underwater flora and fauna, combined with sunlight refraction, generate a rendering cost that grows quickly on Ultra. Medium preserves the volumetric sunbeams piercing the water, which is the truly iconic visual element, sacrificing only shadow-edge detail.
Resolution Scale
Lowering the resolution scale to 90% reduces the pixel load to render with barely any noticeable difference in motion, since the game's underwater distortion effect disguises the sharpness loss. Especially useful on entry-level GPUs struggling at native 1440p or 4K.
2. Medium impact settings
Here's where most of the FPS is. Minor visual impact, major performance impact.
Render Quality
This global setting controls vegetation density, terrain texture detail, and post-processing quality all at once, making it the biggest factor in overall framerate. Medium keeps biomes recognizable and colorful, losing mostly decorative seabed detail rarely noticed while swimming at normal speed.
Draw Distance / LOD
Since the world is generated procedurally via voxel streaming, draw distance determines how much terrain the CPU has to load ahead of time while you swim. Reducing it to Medium directly eases the streaming hitches when entering new zones, which are the main cause of the game's stutters.
Texture Quality
Subnautica isn't especially VRAM-heavy compared to modern games, so keeping textures on High is usually safe even on 6-8GB cards. Lowering to Medium frees up some FPS on systems with little VRAM, but the visual impact on flora and fauna is more noticeable than with other settings.
Ambient Occlusion
Ambient occlusion adds depth to caves and Aurora structures, but its cost in underwater scenes with lots of organic geometry is higher than its visual contribution justifies. Low preserves a minimum of contact shadowing without penalizing framerate as much in bases and caves.
Volumetric Lighting
The volumetric light shafts piercing the water's surface are one of Subnautica's visual trademarks, but on Ultra they generate a noticeable rendering load, especially in shallow zones with lots of direct sunlight. Medium keeps the sunbeam effect convincingly while reducing its computational cost.
3. Upscaling (DLSS / FSR / XeSS)
The biggest gain in the game. Compatible with almost any modern GPU.
4. Tips by GPU
NVIDIA
- •Enable Reflex under the NVIDIA Control Panel to reduce residual input lag from the game's internal FPS limiter, useful in Reaper encounters.
- •Force the power-management mode to "Prefer Maximum Performance" to avoid clock drops during terrain-streaming loads, which generate irregular CPU/GPU usage spikes.
- •If you use an RTX with 8GB or less, keep Texture Quality on High instead of Ultra to avoid microstutters from texture swapping when entering new biomes.
AMD
- •Enable Radeon Anti-Lag to offset the input lag from the game's native V-Sync if you decide not to disable it entirely.
- •On RDNA GPUs with little VRAM, prioritize lowering Render Quality before Texture Quality, since procedural streaming weighs more on bandwidth than raw VRAM capacity.
- •Check that the power mode is set to "High Performance" in Adrenalin, since GPU usage fluctuates a lot between biomes and the driver can underclock during terrain-generation moments.
Sistema
- •Install the game on an SSD whenever possible: on HDD, terrain-streaming hitches get drastically worse and are the most repeated performance complaint in forums.
- •Restart the game every 2-3 hours during long sessions to mitigate the known memory leak, which causes progressive FPS drops and, in extreme cases, out-of-memory crashes.
- •Make sure you have at least 16GB of RAM; with 8GB the system starts paging to disk during world streaming, generating the worst stutter spikes reported.
5. Known game issues
Memory leak in long sessions
RAM and VRAM usage grows progressively the longer you play without restarting, causing increasingly frequent framerate drops and, in extreme cases, unexpected crashes. Periodically restarting the game remains the only reliable remedy.
Stutters when generating new terrain
When swimming fast toward unexplored zones, especially in vehicles like the Seamoth or Cyclops, the engine has to generate voxel geometry on the fly, causing visible microcuts that get much worse on mechanical hard drives.
FPS drops entering/exiting water
The transition between underwater and surface rendering forces a recalculation of reflections, refraction, and lighting that can cause a momentary framerate drop, more noticeable with Reflection Quality on Ultra.
6. Frequently asked questions
Why does Subnautica stutter if it doesn't seem like a very demanding game?▾
Does Subnautica support DLSS, FSR, or XeSS?▾
Which setting has the biggest impact on FPS?▾
Does installing the game on SSD make a big difference?▾
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Calculate FPS for Subnautica →Calculations based on consensus of technical sources and our own FPS model. More about our methodology →