Is there any reason not to turn "disable first rate frame lag" off?

[stainer711]

Having this option on greatly reduces my fps but seems to speed up my mouse responsiveness. I don't know whether or not to keep it on or off. I have Vsync on, so would turning it off coupled with having this option disabled negate the input lag effects? Does anyone else experience lower responsiveness without the option ticked?

[Moloko]

Yes there is certainly some mouse input lag with it unticked.

On the wider point of the general issue of input lag with UT3, someone suggested on 2kgames forum that with Bioshock(UE3) Quote: the "input polling wasn't 'decoupled' from the rendering/game logic. Rendering is I would hope independent of the game logic within the game (even if using delta timing/time based logic rather than frame based), but it's possible that within the logic code there is an anomoly that means the mouse starts lagging as frames drop".

[shombowhore]

VSync synchronizes your monitor's refresh rate with your video card to eliminate the tearing that results from having your card work faster than your monitor. However, the card is still working faster - vsync just prevents the frames from getting to your screen before it's ready for them. The result? The frames are held in a buffer for several ms until they are ready to be shown on screen. That amount of milliseconds is your input lag.

Leaving the 'disable one frame thread lag' ticked apparently puts a greater load on your card, lowering your framerate and therefor reducing this effect. Thankfully, I found a work around recently.

You can eliminate mouselag entirely while using vsync by turning on fps smoothing and setting the minimum threshold (ini the INI) to several fps below your monitor's refresh rate. If you're using a 75hz monitor, set the minimum fps to 73. Then you can leave 'disable one frame thread lag' turned off without any mouse input lag. If your monitor is 60hz, you'll have to set your minimum to an unfortunate 57 or 58, but for the most part your fps will be consistent and any hitching you might experience will be significantly less noticeable than mouse lag or tearing.

[ThaMarine]

I'm buying a rig in Autumn, probably October. Can't wait for playing with everything set to Maximum.

[shombowhore]

I'm buying a rig in Autumn, probably October. Can't wait for playing with everything set to Maximum.

You can buy a top of the line rig for around $13,000 right now.

My boss and I spec'd it out at work for ****s and giggles.

[i_hax]

When I first installed patch 2.0 it changed my .ini (for god knows why) and unticked the option, and I basically found the game unplayable for 3 or 4 days until I noticed.

Unticking this option literally cuts my ability to play in 3, it's terrible. It should be checked by default, or have a better description - there are probably 100's of people playing with this (unplayable) delay.

I would take low framerate & responsiveness over input delay ANY day.

[shombowhore]

When I first installed patch 2.0 it changed my .ini (for god knows why) and unticked the option, and I basically found the game unplayable for 3 or 4 days until I noticed.

Same here, although ticking the option is not necessarily the best solution.

I would take low framerate & responsiveness over input delay ANY day.

I agree, but you can have the best of both worlds. Input lag can be completely eliminated, regardless of this particular setting, either by turning off vsync (but then you have to tweak to fix the tearing) or by following the process in my first post.

[gargorias]

VSync synchronizes your monitor's refresh rate with your video card to eliminate the tearing that results from having your card work faster than your monitor. However, the card is still working faster - vsync just prevents the frames from getting to your screen before it's ready for them. The result? The frames are held in a buffer for several ms until they are ready to be shown on screen. That amount of milliseconds is your input lag.

Actually frames that aren't required are discarded or not sent to the buffer at all and vsync is not the cause of Input Lag.

[shombowhore]

Actually frames that aren't required are discarded or not sent to the buffer at all and vsync is not the cause of Input Lag.

Vsync does indeed cause input lag. And although some LCDs have delayed images, mine does not. However, I failed to properly explain the issue, because I do not know enough about the specifics. However, the problem occurs when the buffers are filled.

From wikipedia, on the double buffering:

If the system has two color buffers A and B, it can display buffer B while drawing a new picture (rendering) into buffer A. When it is done rendering into buffer A, the system needs to wait until buffer B is in the monitor's vertical blank period before swapping buffers. This waiting period could be several milliseconds during which neither buffer can be touched. At 60 frames per second, there are only 16.67 milliseconds in which to draw the frame, so this delay could waste valuable frame time.

And on triple buffering:

... if the system is interactive (for example, a simulator or a video game), and using triple buffering as a fixed order reservoir, triple buffering increases the average delay between the input controls being read and visual feedback being presented to the user. In the other case where frames can be dropped without being displayed, triple buffering can actually lower response time by including input data which wasn't available when the previous dropped frames were rendered.

[gargorias]

Vsync does indeed cause input lag. And although some LCDs have delayed images, mine does not. However, I failed to properly explain the issue, because I do not know enough about the specifics. However, the problem occurs when the buffers are filled.

From wikipedia, on the double buffering:



And on triple buffering:

I get no visible input lag on my 30" Dell at 2560x1600 and I have "disable first rate frame lag" uncheked and I use triple buffering, vsync on and render frames ahead at 3. I get terrible lag if my frames are too low or jump all over the place like in Crysis.
Yes it is hard to get a grip on but unless you are getting a very poor frame rate below your monitors vsync or your framerate is jumping all over the place from high to low then you shouldn't be getting very much input lag except perhaps if you have a poor quality LCD.
Its all about synchronization AFAIK.

[Jov4s]

Have the ``disable one thread frame lag`` option unthicked, and have vsync and smoothing enabled with min: 60 max 120.

I do have problems aiming, while having 60 fps, so this would be cause of input lag?

[Jov4s]

Have the ``disable one thread frame lag`` option unthicked, and have vsync and smoothing enabled with min: 60 max 120.

I do have problems aiming, while having 60 fps, so this would be cause of input lag?

[DrFish]

vsync is the main problem regarding input lag.

Turn vsync off, turn framerate smoothing on, everything will be fine.

[gargorias]

Have the ``disable one thread frame lag`` option unthicked, and have vsync and smoothing enabled with min: 60 max 120.

I do have problems aiming, while having 60 fps, so this would be cause of input lag?

With or without vsync you are going to need framerate smoothing on in this game.

[shombowhore]

Yes it is hard to get a grip on but unless you are getting a very poor frame rate below your monitors vsync or your framerate is jumping all over the place from high to low then you shouldn't be getting very much input lag except perhaps if you have a poor quality LCD.

This is wrong. Input lag with vsync occurs with LCDs and CRTs, and can become worse at higher fps. I used to get 160+ fps in UT2004 on a CRT, and turning vsync on gave me HORRIBLE input lag.

My framerates in UT3 were consistently above my refresh rate until I capped them using framerate smoothing to remove the mouselag brought on by vsync.

edit: And I do not have a poor quality LCD.