Remove Fallout 4 60FPS Cap & Mouse Smoothing, Acceleration, & Lag

By Published November 09, 2015 at 11:00 am

This is sort of a two-in-one fix – at least, it was for us.

Fallout 4, shipping tomorrow, is built on the same engine as Skyrim and previous Fallout games. Anyone familiar with Skyrim's expandability through mods and .ini tweaking may recall “iPresentInterval” – well, it's back.

iPresentInterval isn't just a V-Sync equivalent, which would lock the framerate to the refresh rate; instead, iPresentInterval caps the framerate at a hard 60 max (even with a 120Hz display). In Skyrim, changing this setting could impact physics events and was often recommended left on, despite the framerate limitation. To be fair, neither Skyrim nor Fallout are games that benefit from the notoriously high framerates demanded by CSGO players, for instance, but users of high refresh rate monitors still want their FPS.

These steps will fix two Fallout 4 issues: A “laggy” mouse that resembles acceleration or smoothing and the locked 60FPS cap.

1. Launch Fallout 4 and click “Options.”

2. Configure the options to your liking. Close the menu items and click “Exit” to quit Fallout 4 completely.

3. Navigate to \My Documents\My Games\Fallout4\.

4. Create a backup of Fallout4Prefs.ini (copy/paste locally)

5. Right-click Fallout4Prefs.ini, click Properties, and ensure that the file is not presently set to read-only. This should only happen if you've been here before, otherwise it's writable.

6. Edit the file. Ctrl+F for iPresentInterval.

7. Change iPresentInterval=1 to iPresentInterval=0.

8. Save & close the file.

9. Right-click Fallout4Prefs.ini, click Properties, and check the “Read Only” box, then apply your settings.

Fallout 4 will no longer be able to modify game settings at startup, so you'll need to make the file writable again (reverse step 9) in order to change resolution, shadows, or any other settings. The purpose of locking the file is so that iPresentInterval is not reset, because Fallout 4 resets the file at each launch.

There is a Fallout4Custom.ini, which we suspect is an override for some other file. We tried adding iPresentInterval here, but it didn't seem to take. Success was only achieved with Fallout4Prefs.ini.

FPS can now exceed 60. As a side effect, the mouse should now feel more natural (like raw input) and the lag / smoothing / acceleration effect should dissipate with higher framerates.

In Skyrim, it used to be the case that adding bMouseSmoothing=0 to the [Controls] block in .ini files would remove smoothing, but we've been using the above solution instead for Fallout. If you find something that works – and most things that worked in Skyrim & New Vegas should work here – post it below to help the others who land on this page.

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- Steve "Lelldorianx" Burke.

Last modified on November 09, 2015 at 11:00 am
Steve Burke

Steve started GamersNexus back when it was just a cool name, and now it's grown into an expansive website with an overwhelming amount of features. He recalls his first difficult decision with GN's direction: "I didn't know whether or not I wanted 'Gamers' to have a possessive apostrophe -- I mean, grammatically it should, but I didn't like it in the name. It was ugly. I also had people who were typing apostrophes into the address bar - sigh. It made sense to just leave it as 'Gamers.'"

First world problems, Steve. First world problems.

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