I recently fired up TF2 for the first time in a while and I noticed an odd issue. Quite often, I will need to click Mouse1 twice in order for my character to shoot. Also, at times I will notice the actual mouse cursor lagging slightly behind my crosshairs as well.

I haven't played for a while and recently decided to get going again, and this issue...kinda ruins the experience for me on anything but a spray and pray run.

Any ways to fix this? I'm not an OSX expert by any means, and this just kills the game for me.

2 Answers 2


For whatever reason, OS X has a small amount of mouse latency. An application called SmoothMouse is supposed to fix it, although I haven't verified this.

There was a popular blog post by the author of SmoothMouse a few years ago which details the issue. John Carmack weighed in in the comments:

You can measure all this objectively. I took a few minutes, pulled out my handy high speed camera, and shot some quick video dragging a window around on my windows desktop and my old macbook. I used the same mouse, a Razer DeathAdder, on both systems.

Someone with more time should do a more exhaustive set of tests with a tripod and a trivial app instead of window dragging to make the data cleaner, but the results are so dramatically different that it isn’t a matter of splitting hairs.

Even being generous with exactly which frame the mouse started moving on, I never counted less than 10 frames (at 240 hz = 42 milliseconds) and sometimes as many as 17 from the time the mouse moved to the time the pixels on the screen started to change. I’m sure this is better on a more modern system.

The PC result was surprising. I was running on a 120hz monitor, and I couldn’t positively identify any frames of latency between the mouse starting to move and pixels on the screen changing. ...

  • This is a great answer, and it definitely fixed the stupid smoothing that OSX natively implements, however it did not resolve the double click issue. (Thank you however, for making pinpoint accuracy possible again).
    – erik
    Commented Apr 9, 2014 at 17:46
  • Actually, now that I looked again, my issue somewhat seems to be that TF2 loses focus, and I need to click to bring it back.
    – erik
    Commented Apr 9, 2014 at 17:49

Another current bug that induces input latency is that sometimes, TF2 shows up in the wrong Space—instead of staying in its own dedicated fullscreen Space, it'll be in one of your regular desktops. When that happens, TF2 can't suppress vertical sync anymore, which can have a pretty big impact on crosshair responsiveness.

You can sometimes fix the problem by command-tabbing and switching spaces until TF2 finds its way back into its own Space. If that doesn't work, relaunching the game is the annoying, surefire way of restoring proper order.

Alternatively, you can use Quartz Debug to force vsync (“Beam Sync”, in Apple terms) off, but this'll require you to sign up for a free Apple developer account, download Xcode, and then download the Graphic Tools, so it's quite a hassle to set up.

In any case, SmoothMouse is a must-have, as it'll also allow you to disable mouse acceleration, which is arguably necessary to achieve fast consistent aim.

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