Diablo 3 PC Performance Tweaks Guide

Though Diablo 3 isn’t the most graphic-intensive game of the current generation, some people may have performance difficulties/issues in-game. Use the following Diablo 3 PC Performance Tweaks guide to improve your frames.

While the best solution would obviously be an upgrade in hardware, there are plenty of other things that can be tried, out of which the most essential is meddling with the D3Prefs.txt file.

This text file is located in /Users/My Documents/Diablo III, and has many variables. The following is a list of the functions included in the file, along with their function and probable effect on the performance/quality of the game:

Diablo 3 PC Performance Tweaks

PreferencesVersion “X
The value is ‘42’, and should be NOT be altered. Doing so may make the game unplayable.

PlayedCutscene “X”
There are 4 values from 0-3. This command indicates which video should be played in the Acts. Since Blizzard’s done a fantastic job with their video cutscenes, I suggest leaving it alone – unless of course this is the 10th time playing the game, in which case you can delete these so the videos don’t play.

DisplayModeWindowMode “0”
Have the value set to 1 to play the game in a windowed mode.

DisplayModeWinWidth “1280”/DisplayModeWinHeight “720”
This is the game resolution value when the game is run in windowed mode.

DisplayModeWidth “1600”/DisplayModeHeight “900”
This is the game resolution value when the game is running in full-screen mode (default mode).

DisplayModeRefreshRate “60”
This is the value of the Refresh Rate of your screen while running the game. If your screen supports higher RR, change the value to it.

DisplayModeBitDepth “32”
This is the color bit-rate of the game. Unless you enjoy old-school VGA 16-bit colors, I suggest you leave it like it is.

Gamma “0.680000”
The gamma value used in-game.

ShadowQuality “X”
Value ranges from 1-3, with 1 being the lowest detailed and 3 the highest. Set it to the desired value.

PhysicsQuality “X”
This is the physics details in the game, ranging from 1-3. Set to desired value for game performance.

ClutterQuality “X”
This changes the quality and density of clutters in the game; ranges from 1-3.

Vsync “X”
Binary value of 0/1, where 1 is for enable. Vsync will limit your FPS equal to that of the screen Refresh Rate. Disabling may increase FPS, but can cause screen-tearing.

Antialiasing “X”
Assign value 1 for enabling AA, while 0 will turn it off. Turning AA off can give massive performance boosts, but may produce jagged texture and polygon edges.

LowFX “X”
Set to 1 to reduce the quality of effects in the game. This will boost performance but reduce visual quality.

LimitForegroundFPS “X”
Enable/disable limit of the foreground FPS. Enabling this will activate the following command.

MaxForegroundFPS “XXX”
Set the foreground fps limit to a certain value. 150 is the default value, and I see no reason to change it.

LimitBackgroundFPS “X”
Enable/disable limit of the background FPS. Enabling this will activate the following command.

MaxBackgroundFPS “XX”
Set the background fps limit to a certain value. 41 is the default value, and I see no reason to change it, as changing it will not increase FPS of the game (it may actually decrease them).

DisableTrilinearFiltering “X”
Set 1 to disable trilinear filtering, or 0 to leave it enabled. Setting to 1 may improve performance, but lower visual quality.

ReflectionQuality “X”
Determines the quality of reflections. Set 1 for high quality and 0 for low.

ColorCorrection “X”
Enable/Disable color correction. I suggest leaving this to 1.

MasterVolume “0.600000”/EffectVolume “1.000000”/MusicVolume “1.000000”/NarrationVolume 1.000000″/AmbientVolume “1.000000”
Adjust the different volumes of the game.

ReverseSpeakers “X”
Swap left/right channels of headphones/speakers.

QuestSubtitlesEnabled “X”
Enable/Disable subtitles for in-game quest-related conversations.

CinematicsSubtitlesEnabled “X”
Enable/Disable subtitles during cinematic cutscenes.

EchoQuestDialogToChat “X”
The in-game dialogues also appear in the chat on the bottom left corner when value is set to 1.

MuteSound “X”/MuteEffects “X”/MuteAmbient “X”/MuteVoice “X”/MuteMusic “X”
Mute the various audio parameters in the game.

PCIVendor “XXXX”/PCIDevice “XXXX”
The values are identities of your hardware devices; do not alter this.

MipBias “X.XXXX”
Higher values of MipBias should decrease texture quality. For performance, set the value of \MipBias\ to a higher value. Thanks @ Brandon


  • DisplayModeFlags “X”
  • DisplayModeWinLeft “XX”
  • DisplayModeWinTop “XX”
  • DisplayModeUIOptWidth “XXXX”/DisplayModeUIOptHeight “XXXX”
  • MipOffset “X”
  • Letterbox “X”
  • ChannelsToUse “X”
  • TonemapExposure “X”
  • TonemapContrast “X”
  • TonemapSaturation “X”
  • TonemapGain “X”
  • HardwareClass “X”

We are unsure of the function and effect of the above listed variables. If you know their function, performance changing effect, and/or sensitivity please share with us by commenting.

How To Run Diablo 3 on Unsupported Hardware
You can read the detailed instructions on how to tweak Diablo 3 to run on unsupported graphics card here.

Diablo 3 Troubleshooting
Read this Diablo 3 guide for detailed instructions on troubleshooting different errors, graphics and performance issues.

Maintain Smooth game performance

Check the max frame rate limit box and set it to 60 fps. Your game should be a lot smoother than before even at high settings. When this is uncapped, your pc may try to run the game at the highest it possibly can, taking it to even 200+ fps that causes your game to get stuck or not run as smoothly as it should because your pc is handling maximum load. Capping it at 60 frames allows it to run the in high definition without chocking.

Increase Fps and general performance

  • There is a setting in the d3 config file called “hardwareclass”. Its number will be between 1 and 6. Setting it lower tells the game to not use certain effects etc, which results in some lesser effects (but honestly not that noticeable) and usually an fps increase to go with that.
  • Limiting the number of audio channels or turning audio off completely can give a noticeable FPS boost as well, depending on your hardware of course.
  • You can try right-clicking diablo in the task manager and setting priority to: high. You can also try using software like Razer Game Booster, which might helpt with especially CPU performance.
  • There is a d3prefs.txt file that seems to rate your system when the game is first launched. Users are reporting improvements when setting HardwareClass to 1
  • Windowed or fullscreen windowed. Simply changing the game out of fullscreen mode seems to stabilize the game’s framerate quite a bit.
  • Check that your firewall is not affecting any blizzard’s ports/connections

Haider is a freelance contributor, who loves video games, playing guitar, and aviation. He is a competitive FPS player and also enjoys exotic RPG games like Diablo and Xenogears (his favorite game of all time) ...