constantly stuttering making the game unplayable. Changing settings makes no difference, FPS makes no difference.

Tried tons of fixes i found online none work. I am currently re installing the game to my SSD to see if that helps.

Specs:
Intel i7 7820HK
GTX 1080 8GB
16gb DDR4
Currently being installed on Samsung EVO 960 SSD

To follow up on this: SSD made zero difference

Hmm, have you tried uninstalling and reinstalling it?

It's an installation issue.
Update your drivers: http://www.majorgeeks.com/files/details/slimdrivers.html
Check for conflicts.

If this isn't drivers, then it must be another program running which is taking priority.

I've already tried re-installing it, to my SSD instead of mechanical. Same issue. I am on the latest drivers. This is a fresh reformat as well, i had this issue before the reformat, as well as on a completely seperate PC. Oddly enough, my old laptop with a 960m did not have this issue, only my higher end systems have had it. My Desktop I had with a 1070 had this issue, and this system with the 1080 has the issue as well. Makes the game unplayable.

I can only repeat, there is a conflict issue.

I don't know your level of knowledge. If you know what Event Viewer is and how to use it, you should be able to find the conflict there. If you are not sure, don't touch it. It's was never designed for users and even experienced engineers don't like it.

Personally, I strongly suspect your anti-virus or other protection software. If you bought your PC complete then chances are you have one of the really bad one like McAfee or symantec. These are not only about as useful as a chocolate teapot, they are difficult to remove.

Apart from that you may also have some issues with other software that is running continuously. Ccleaner is one of the easiest ways to see what is running. But again, you do need to know what you are doing.

I am happy to help you if you can supply appropriate information.

Please start by saying who made your PC and if it has any shop logos installed I also would like to know how confident you are with PCs generally.

This suggests a physical problem. Try removing any peripherals you have on your system, especially non-essential ones.

try disabling gog.galaxy overlay

I just bought the game and experiencing the same exact issue. The game is so laggy I can't even move - literally unplayable.

Core i7-8700 3.2 ghz 6 cores
8 gig RAM
Radeon RX 580

Lowest settings with 30 FPS and nothing turned on won't even reduce the stuttering/lag. Changing settings makes no difference.

The GOG Galaxy overlay has caused issues with this game for me. Disabling it gave me a 20+ FPS boost. Try that and see what happens.

My level of expertise as at a technician level, and I do programming/support as a job. I do not use those anti-viruses. My Machine with a 1070 was built by me, the one with the 1080 is a laptop. Both systems have the same issue despite being totally different set ups. Also disabling the overlay helped a little, but it still micro-stutters. I feel like this issue is in the game, and not with my systems.

I have the same issue on a Palit Gamerock Premium GTX 1080. It follows the graphics card as the issue occurs on my I7 5820K and my I7 940. It's generally in the cities like Beauclair, particularly if my save is in the middle of the city. However, the game seems significantly smoother on my old AMD HD 6970 although the settings are lower. The GTX 1080 was tested on my Dell S2716DG Gsync monitor and an Eizo non Gsync monitor and the issue persisted.

It's strange that my brother who's using an Asus GTX 1080 Ti, an AMD Ryzen 1600 and a Dell S2417DG Gsync monitor doesn't suffer the issue and the game runs smoothly even in the middle of Beauclair.

What brand is your GTX 1070 OP?

ok.. I had this problem.. game was almost unplayable.. not totally sure what finally fixed it, but here you can check my user file settings and other impressions

on that settings game runs great in 4k on zotac amp extreme 1080 and i7 6950x

I did not try to kill gog overlay for sure

it may be windows fault- had that before.. from then I am downloading latest windows iso from microsoft each time i re-install system and prepare bootable usb drive, so the fresh installation has ll the fixes and latest drivers included- it makes huge difference!

you may also want to check if switching the hardware mouse cursor- enable or dissable it- set opposite as you have now

ok.. now the settings (in user.settings file under witcher3 in documents folder

[Gameplay/EntityPool]
SpawnedLimit=150
[Hidden]
HasSeenEP2WelcomeMessage=true
HasSeenDLCMessage=true
HasSeenGotyWelcomeMessage=true
HasSetup=true
HasSeenEP1WelcomeMessage=true
uiVerticalFrameScale=1
uiHorizontalFrameScale=1
[Localization]
RequestedSpeechLanguage=
SpeechLanguage=PL
RequestedTextLanguage=
TextLanguage=PL
[Viewport]
VSync=true
Resolution="3840x2160"
FullScreenMode=2
VSyncThreshold=0
OutputMonitor=0
[Budget]
TerrainTileMipDataBudget=100
TerrainTileMinTimeout=2
TerrainTileTimeout=10
OcclusionQueryAdditionalMemory=5
TerrainTileLoadingTimeout=5
[ContentManager/Mods]
MaxNameLength=64
Enabled=true
[Audio]
Subtitles=true
[LoadingScreen/TCR]
ShowProgress=true
[Game]
DoNotPauseWhileStopped=false
[Scripts]
DebugScriptsForceFlush=true
DebugScriptsLogDir=
[PostProcess]
SharpenAmount=2
MotionBlurPositionTreshold=0.05
AllowVignette=false
MotionBlurRotationTreshold=1
AllowMotionBlur=false
SSAOSolution=2
AllowBlur=false
[Input]
PadVibrationEnabled=true
KeyboardCooldownSpeed=0.1
InvertCameraXOnMouse=false
InvertCameraYOnMouse=false
CameraAutoRotX=true
InvertCameraX=false
UIMouseSensitivity=1
CameraAutoRotY=true
RightStickCameraSensitivity=1
InvertCameraY=false
RightStickAimSensitivity=1
MouseSensitivity=1
SteamController=0
ForceDisablePad=false
[DLC]
DlcEnabled_dlc_010_001=1
DlcEnabled_dlc_015_001=1
DlcEnabled_dlc_005_001=1
DlcEnabled_dlc_007_001=1
DlcEnabled_dlc_013_001=1
DlcEnabled_dlc_004_001=1
DlcEnabled_dlc_006_001=1
DlcEnabled_dlc_001_001=1
DlcEnabled_dlc_008_001=1
DlcEnabled_dlc_011_001=1
DlcEnabled_dlc_002_001=1
DlcEnabled_ep1=1
DlcEnabled_dlc_014_001=1
DlcEnabled_dlc_009_001=1
DlcEnabled_bob_000_000=1
DlcEnabled_abob_001_001=1
DlcEnabled_dlc_012_001=1
DlcEnabled_dlc_003_001=1
DlcEnabled_dlc_016_001=1
DlcEnabled_dlc_011_002=1
[Gameplay]
Difficulty=3
EnableUberMovement=1
[LevelOfDetail]
SwarmHideDistance=200
DecalsHideDistance=80
DimmerHideDistance=60
DynamicDecalsHideDistance=20
StripeHideDistance=60
[General]
ConfigVersion=2
[LoadingScreen/Editor]
Disabled=false
[LoadingOverlay/TCR]
FadeOutCooldownExtraTime=1
FadeInSpinnerTime=1
NoninteractiveSpinnerTime=3
FadeOutSpinnerTime=1
NoninteractiveEndCooldown=1
[Visuals]
AllowClothSimulationOnGpu=false
InventoryBgColorScaleB=0.036
InventoryFixedLuminance=0.25
InventoryBgColorScaleG=0.034
MovieFramerate=30
GammaValue=1.9
InventoryBgColorScaleR=0.02
[Rendering]
GrassDensity=2400
DecalsSpawnDistanceCutoff=10
GlobalOceanTesselationFactor=48
CascadeShadowFadeTreshold=1
HairWorksGlobalWidthLimit=5
CascadeShadowDistanceScale2=1.2
MaxTextureAnizotropy=16
HairWorksGlobalDensityQuality=1
TextureMemoryBudget=800
CascadeShadowDistanceScale3=1.2
HairWorkstGlobalDensityLimit=2
TextureStreamingHeadsDistanceLimitSq=100
MeshLODDistanceScale=1
ScaleformTextureUnstreamDelay=2.5
DecalsChance=1
TerrainReadAheadDistance=200
HairWorksLevel=2
TerrainScreenSpaceErrorThreshold=2
TerrainScreenSpaceErrorThresholdFar=5
TextureStreamingCharacterDistanceLimitSq=225
MaxTerrainShadowAtlasCount=4
TextureStreamingDistanceLimitSq=40000
HairWorksGlobalDetailLODFactor=1
TextureMipBias=-1
HardwareCursor=true
TextureInFlightBudget=128
TextureInFlightCountBudget=12
PreserveSystemGamma=false
CascadeShadowmapSize=2048
CascadeShadowDistanceScale0=1
MeshRenderingDistanceScale=1
CascadeShadowQuality=1
CascadeShadowDistanceScale1=1
[Input/Gestures]
EnableSwipe=true
EnablePan=true
EnableGestures=true
EnablePinch=true
[LoadingScreen]
FadeInTime=3
SkipShowWithAnyKey=true
GameRevealTime=3
SkipHideDelay=3
SkipInputDelay=0.25
FadeOutTime=1.5
SkipAutoshow=false
[Engine]
LimitFPS=60
[Rendering/SpeedTree]
GrassGenerationEfficiency=0.075
GrassDistanceScale=1
FoliageDistanceScale=1
FoliageShadowDistanceScale=16
GrassRingSize=4194304
[Gameplay/BoatCamera]
BoatLocalSpaceCamera=false
[Save]
ShowCompatWarning=false
[Kinect]
Kinect=true
[Foliage]
MaxVisibilityDepth=12

My stuttering problem was gone with enabling the hardware mouse cursor.

Disabling the mentioned overlay for GOG. And the nvidia experience, shutting down shield things, overlays and all the junk. Helped some too.