How to Fix Mouse Input / Lag / Acceleration / Deceleration in Battlefield 3 and Some Random Old Mouse History

Update: Apparently the latest patch/DLC (early June) has caused more mouse problems for BF3. I am attempting to compile a list of possible fixes. Try turning on vsync if you have not done so already, and leave a comment if the fixes below help with the new lag that has developed.

vsync introduces at least a 1 frame delay to input. At 60FPS you are seeing the movement in the 61st or 62nd frame. This is a delay to the order of 16.6 or 33.3ms, but it can strech out to 3-4 frames depending on the shoddyness of the developer. This is probably not what is causing the mouse lag in the most recent patch but I thought including it here might be useful to someone.


I have gamed for a long time and a long time ago I learnt that low mouse sensitivity with no acceleration is the best way to play. It leads to less “mistakes”, higher accuracy, less effected by cold hands or nerves – not applicable to me but many of the guys I used to game with would get nervous before important matches. It is overall better. The one proviso is you need to stay situationally aware at all times, else you get shot in the back and can’t turn around quickly enough. In most older games this was not a problem, but in BF3, with its horrid sound system this IS a problem. A problem for another post.


Unlike some super anal FPS people I have never sat down and measured my base sensitivity and then applied this to all games. I just go with what feels about right. This is probably because I have only really ever played one FPS at a time.

Around the end of Unreal Tournament 2003 I switched to a Microsoft Intellimouse v3 and then to a Razer Deathadder two years later. Both mice have similar shapes which I was happy with. In 2009 I started to suffer from wrist pains using the Deathadder. As a result I opted to grab a new Steelseries Xai – a mouse that had received a lot of hype and was a completely different shape to the MS v3 and Deathadder. My wrist pains went away.

It is a rather fail, mouse as it has non removable positive acceleration. At the time I was playing Quake Live and testing out in game acceleration, which I liked, and which Q3 does awesomely. I like how you can set thresholds and maximum values and almost have high/low speed with little inbetween. This masked the problem enough that I did not care. Now I play Battlefield 3 which also has non removable positive acceleration, or so I thought. Many people played UT99 with horrible, video setting induced acceleration but were not aware of it because it was cool to have your sensitivity as high as humanly possible back then. Acceleration is not obvious with high sensitivity, but at the same time no acceleration will allow better aiming with high sens, it just does not feel as obvious.

Acceleration fixes

I do not pretend to be an expert on this, I know what works for me but I don’t really understand why.

One of the first things many gamers install with a fresh version of windows is some sort of mouse fix. Here is the one I used last. This sort of patch fixes acceleration problems in most games, because most acceleration problems are caused by the OS – at least in my limited understanding. The Battlefield 3 devs decided that we should have positive acceleration and no option to remove it via the menus, and in conjunction with the buggy Xai mouse movement ends up feeling sloppy, unresponsive and really not very nice.

I played until a few weeks ago without doing anything about this. I guess I had grown accustomed to the acceleration and was playing decently enough to not bother about trying to fix it – and I had found a fix, almost three months ago. I wish I had acted sooner.

Firstly you need to get some sort of text editor. I use Notepad++  for webdev and recommend it.  If you have Ultraedit installed that should work too.

Find these lines:

GstInput.Scheme0Sensitivity 0.000000
GstInput.Scheme1Sensitivity 0.000000
GstInput.Scheme2Sensitivity 0.000000

And set them to zero.

Incase you were wondering – GstInput.MouseSensitivity 0.061047 – is your in game sensitivity in a number rather than a stupid slider bar.

Input feeling after applying this fix may vary – if you are a high sensitivity player then accel is not as noticeable. If you play with low sensitivity and you want no acceleration then this is a god send. Apparently high DPI also affects this, I play at 650 (up from 500) so these changes may really be masking the problem rather than solving it. For me it is close enough to not worry about anymore. 650DPI is perfectly acceptable for low sensitivity FPS.

  1. Apply an operating system level fix such as this
  2. Edit your config files as above
  3. Set your mouse to a lower DPI setting. If you use low sensitivity you can go all the way down to 400DPI if required. Remember to adjust your in game sensitivity to suit.
Do you need 3500DPI when you use 30 inches for a full turn? In short no.

Another nice thing you can change in this file is your FOV. The maximum setting in game is 90 with the default being 60 – this is positively cramped. I run 120 which might be too high for most peoples tastes. There are drawbacks, hip firing is significantly harder with higher FOV, but the game feel so slow at lower that I am willing to suffer less hip kills. Change this line

GstRender.FieldOfView 120.000000

Finally if you are playing BF3 pick a weapon loadout that suits your style.