Ultimate Mouse Lag/Input Lag Fixing Guide.

Guide to fixing the sluggish/laggy mouse input in Fallout 4 to get as close to "1:1" mouse input as possible. Makes aiming and general gameplay much more enjoyable. Also seems to fix "microstuttering" some people have been getting when looking around. Most recent update adds fix for removing mouse lag in menus.

2021 Update Note

I published this guide before knowing SpecialK[wiki.special-k.info] existed. Do yourself a favour and read up on SK,[wiki.special-k.info], download / install it[discourse.differentk.fyi] and achieve the lowest input delay across all your games.

Theoretically you should be able to skip the "iPresentInterval=1" config tweak and keep VSync enabled whilst using SK's own framerate limiter if required.

Intro

Ok so as you may know the V-Sync in many games is splendid for eliminating screen tearing but often introduces input lag/mouse lag in game which is probably my #1 pet peeve in all gaming, especially FPS games. Now if you don't have any issues with mouse lag, lucky you! You might want to tweak a couple of things mentioned here like disabling the mouse acceleration & making the X&Y sensitivity even but i wouldn't touch anything else as that's for people who do get input lag.

In Fallout 4 (and many other Bethesda game on the Creation Engine) V-Sync is forced on with no option to disable it without editing the config files. Problem is many aspects of the engine are tied to your FPS so disabling V-Sync thus increasing FPS over the set limit can cause all sorts of undesirable consequences. In Skyrim it caused serious issues (that bumpy cart ride) and in Fallout 4 it seems to mess up lockpicking, accessing terminals, making you move at hyper speed and other things.

By default Fallout 4's V-Sync limits your FPS to half of your monitors refresh rate. For example i have a 144hz monitor so with V-Sync on i'm limited to 72fps max at all times.

So we want V-Sync disabled for better input "feel" (and trust me after doing this it's worlds better) but we don't want to mess up the engine by letting the framerate get too high. Onto the guide for getting your mouse movement as accurate as possible.

Please note i will be updating and expanding this guide whenever i discover/experiment with new things so keep checking back!

Disabling V-Sync

1) Go to your fallout4 folder in documents, mine is located in:
"C:\Users\Ash\Documents\MyGames\Fallout4\"

2) Open Fallout4Prefs.ini with your preferred text editor.

3) Find the line

iPresentInterval=1

and simply change the 1 to a 0.

4) Save the .ini.

Disable Mouse Acceleration

1) Go to your fallout4 folder in documents, mine is located in:
"C:\Users\Ash\Documents\My Games\Fallout4\"

2) Open Fallout4.ini with your preferred text editor.

3) Find the Controls section and at the bottom of it add the following:

bMouseAcceleration=0

And save.

4) Located in the same folder as the last .ini you will find Fallout4Prefs.ini, open it with your preferred text editor.

5) Find the Display section and at the bottom of it add the following:

bForceIgnoreSmoothness=1

And save.

6) Go to your Steam fallout4 folder (different from the one you just had open) mine is located at
"D:\SteamLibrary\SteamApps\common\Fallout 4\Fallout4\"

7) Open Fallout4Prefs.ini with your preferred text editor and repeat step 5 for this .ini file, don't forget to save it!

Make the X&Y Sensitivity Even

Presumably an oversight unchanged on PC as it's more of a console benefit, the up/down look sensitivity is halved when compared to your left/right sensitivity.

To fix this go back to your documents\my games\fallout4 folder but this time open fallout4.ini, not the prefs one.

Under the controls section you should see two similar lines of code, fMouseHeadingYScale & fMouseHeadingXScale. Leave the XScale as it is, we're only interested in changing the YScale value. What you change that to depends on what aspect ratio your monitor is, see below for reference.

• 16:9 aspect ratio resolutions(1024×576, 1152×648, 1280×720, 1366×768, 1600×900, 1920×1080, 2560×1440 and 3840×2160), set the "Y" scale as so:
  fMouseHeadingYScale=.03738
  
  
• 16:10 aspect ratio resolutions(1280×800, 1440×900, 1680×1050, 1920×1200 and 2560×1600), set the "Y" scale as so:
  fMouseHeadingYScale=.0336
  
  
• 4:3 aspect ratio resolutions(640×480, 800×600, 960×720, 1024×768, 1280×960, 1400×1050, 1440×1080 , 1600×1200, 1856×1392, 1920×1440, and 2048×1536), set the "Y" scale as so:
  fMouseHeadingYScale=.028
  
  
• 5:4 aspect ratio resolutions(1280x1024, 2560x2048 and 5120x4096), set the "Y" scale as so:
  fMouseHeadingYScale=.02625
  
  
• 21:9 aspect ratio resolutions(2560x1080 is the most popular), set the "Y" scale as so:
  fMouseHeadingYScale=.042

Save the file.

Limit the framerate

Finally, with all the .ini tweaking done, it's time to limit Fallout 4's FPS via third party software to prevent wacky stuff happening. There are many different programs capable of doing this so if you're already aware of how to limit your FPS with your favourite GPU tweaking software go ahead and use that instead of Afterburner.

Afterburner's primary use is for GPU overlocking, if you've never done this before/don't know what you're doing then don't mess with any of the core settings in Afterburner itself. We only want the FPS limiter in the RivaTuner software that comes installed with Afterburner.

Make sure you've got Afterburner & RivaTuner both fully up to date after installing or the FPS limiter might not work

1) Download and install MSI Afterburner, Then launch it.

2) Open RivaTuner, located in your taskbar.


3) Add Fallout 4 by clicking the "+" icon . Find where it's installed on your PC, for me it's
"D:\SteamLibrary\SteamApps\common\Fallout 4\fallout4.exe"


4) Make sure your "Application detection level" is set to medium or higher or it may not detect the game launching. If your framerate isn't limited to what you set in the next step try setting this to high.

5) Use the option in the below image to limit your FPS. I've set mine to 72 as i don't seem to have any odd physics issues with it capped at that but you could try 60, maybe even 100+. Not too sure what the game has to hit before it has problems. Some people with 144hz monitors have set it to 144 and have no problems but your mileage may vary, you can always change this setting later.

Please note if you use an FPS counter make sure you actually get in game so you're rendering the world before confirming your FPS cap works. This step won't limit your FPS in the main menu.

Remove Mouse Lag in Menus

After much testing i've come to a conclusion that may or may not be wrong; everything up until here fixes your mouse issues when actually in the game world, with the 3D engine rendering things. When looking at your pip-boy or in any menu the mouse lag is still there, this may be a different part of the 3D engine where .ini changes don't take effect, so after experimenting i think this is due to V-Sync still being enabled just for menus. With this being the case we need to force V-Sync off at a driver level to stop menus being laggy.

Please note that this section is only for NVIDIA GPU owners, i'm not sure if menu mouse lag is even an issue for AMD/ATI GPU owners but if anyone messages me about it i'll work with that person to help remove it on AMD/ATI GPU's aswell. Refer to the image below if you get lost in any of the following steps!

1) Open your NVIDIA Control Panel via right clicking your desktop and finding the option.

2) Click on the "Manage 3D settings" button on the left.

3) Click on the "Program Settings" tab here.

4) Click on the "Add" button and if you've recently played Fallout 4 it will show up here. If it doesn't then sort by: A-Z. Still not there? Click browse and find your fallout4.exe, mine is located at
"D:\SteamLibrary\SteamApps\common\Fallout 4\Fallout4\" for reference.

5) Fallout 4 (fallout4.exe) should now be showing up as the program to customise, verify this.

6) Scroll down until you find the feature "Vertical sync" and change the setting to "Off". Note that Use the 3D application setting won't work properly so please make sure you set it to "Off".

7) Click apply at the bottom right and close NVIDIA Control Panel.

Not seeing some of the settings i've mentioned here? Make sure you update your gfx drivers fully and check again.
Click the image below to make it bigger.

ADS Sensitivity (Optional)

In Fallout 4 when you aim down sights(ADS) with right mouse button the sensitivity drops from your usual "hip fire" sensitivity, this is intended to help slow down your aim and be more accurate with your shots. This feature is in many FPS games and usually configurable in the game options. Not in Fallout 4.

This is an entirely optional fix that's down to your personal preference on the matter and won't introduce any undesirable problems or lag that you've fixed using my guide. If you would like to have your ADS sensitivity match your look sensitivity check out Jwam's steam guide on how to do it. This isn't a necessary step to eliminating input lag, entirely optional.

Done!

If you've followed all the steps correctly when you launch Fallout 4 and get in game you should be limited to your desired framerate without any sort of input lag. Hopefully i've been clear enough in these steps but if not just let me know! Please note you have to follow every section of this guide, apart from anything labelled optional, in order to eliminate the input lag completely. Just doing one or two sections won't necessarily work so please follow it all!

Please bear in mind the main caveat of this guide is that disabling V-Sync will introduce screen tearing for some people. If you get it then where you set V-Sync to off in NVIDIA Control Panel set it instead to "Adaptive", Triple buffering to "On" and Maximum pre-rendered frames to 1. For some people this will introduce some input lag again but your mileage may vary. It's a trade off where you'll have to decide which bothers you most.

Check out Gabi's steam guide for information on FOV changes, intro video skip etc.

Originally posted by me to the /r/fo4 subreddit. Decided to make a steam guide to spread the word to more people. If you have any problems with this guide post on there and i'll see what i can do to help!

Help! I still have input lag!

Damn. Well the first thing to do is go back through the guide and make sure you followed the instructions to the tee. Make sure you edited the right .ini's in the right folders and either added lines or changed lines depending on what i've said to do.

The V-Sync one for example, if you've added that line rather than changing it then it might well not have disabled V-Sync and you'll still get input lag even if you followed all the other stuff correctly.

Been through my guide again and confident you've followed it thoroughly? You sure? Ok, i trust you.

The most common issue people have been reporting is the framerate not being capped properly by RivaTuner. First thing to try is increasing the privileges for RivaTuner. Navigate to it's installed directory, mine is "C:\Program Files (x86)\RivaTuner Statistics Server\" for example. Right click RTSS.exe>properties>compatibility tab and check "Run this program as an administrator" click apply and relaunch Fallout 4, see if it's fixed.

If this doesn't solve things then try uninstalling Afterburner & RivaTuner, reboot your PC and then install to a different drive or directory. (Thanks to steam user HexiibTheDuk for this one!)

One issue that may be happening, for NVIDIA graphics cards only i might add, is that your display drivers are forcing V-Sync to be on at a driver level rather than the game itself.

To see if this is happening open your NVIDIA control panel by right clicking your desktop and finding the option there. Then click "Manage 3D settings" on the left hand side. Scroll down the "Global Settings" tab on this page until you find the feature "Vertical sync" and look at the setting for it. If it's set to anything other than "Off" try changing it to that, apply changes and re-launch your game. Note "Use the 3D application setting" should technically do just that and let Fallout 4 itself decide on whether or not it should run V-Sync but for some reason this setting isn't always accurate so try setting it to "Off" instead and see if this fixes things. Please bear in mind changing this to "Off" will disable V-Sync for all your games. If doing this works and you've already tried the "Removing mouse lag in menus" section of my guide, please contact me via steam and we'll try to nail down the problem together.

For any other input lag based issues or problems either add me on steam and i'll try help you or post on my Reddit version of this guide and i'll see what i can do to help.

[Piglet]

Сейчас четкость управления такая же как в fl3 и fl3nw

[Piglet]

Вообщем давно бился с этим киселем. Мне помог этот мод - RAW INPUT - The Ultimate Mouse Sensitivity Fix. Также поставил мод который чинит движок с отключенной вертикалкой без лока фпс (это очень ускоряет загрузки локаций). Пока в панели нвидии не отключил вертикалку для exe файла - не работало.

[Arrakh-Sa'Namun]

Hello my guy! The Special K did all the way! All I ever needed to do was install and run the game from there! IT's almost magic! :)

[Florida Man]

The RivaTuner was all I needed to fix vsync off. Thank you so much.

[Sentient Meat]

I ended up using the third party FPS limiter because the unhindered framerate did actually cause some very strange effects! (go figure OP said it would happen and it did) It was a very easy step and solved that issue, the game is running beautifully. Thanks again!!!

[Sentient Meat]

This still works after the new update! Honestly and wholeheartedly, this fix makes me so excited for my re-playthrough!!! It made the game playable and I wish I had looked this up ten years ago. I also did not limit the FPS, but I will update if I run into any major issues.

[Mist]

Thanks its 2024 and it still works ! I did all the steps except limiting the fps

[neptronix]

It's 2024 and this fix is still working on Win 10 with a 60fps monitor.
Definitely have to force rivatuner to run as admin or it won't work.

Thanks so much for this!

[Bane554]

Thank you so so so much! I tried a few of these by them selves from other guides and looked up so many things to try to fix the clunky mouse feel in FO4 and nothing worked until I tried all of this.

It is now working perfect and feels amazing to play, where before the mouse drag and framerate weirdness was killing my enjoyment.

Again thank you, this worked perfect and I am so happy to be able to play the game when it feels right.

This guide rocks, and you are a hero @Strangorth
Confirmed working 7/2023

[trek]

Everything worked great except for the X/Y evening steps. I followed them exactly but my Y sens is abysmally slow compared to the X