Finally fixed my stuttering in ACC!

[MapoUK]

After never having ACC run without stuttering, and returning after buying the GT4 pack I was determined to try and resolve the issue. I was running at 80 to 120 fps in 4k but was still plagued with the dreaded microstutters.

Most of you may already know this, but for those who it may help.

To resolve the issue (for me anyway) if you locate the file ac2-win64-shipping.exe (which in located in your ACC game folder SteamLibrary\steamapps\common\Assetto Corsa Competizione\AC2\Binaries\Win64) - right click on it, select properties, select the compatibility tab and click on Disable Full Screen Optimisations. In game set the frame limiter to your screen refresh rate and turn on V-Sync. Windows Game Bar Mode also needs to be disabled for this to work.

I also used the same same option on the acc.exe file (which in located in your ACC game folder SteamLibrary\steamapps\common\Assetto Corsa Competizione\AC2) just in case.

It's cured my microstutters and I've been able to put most settings back to epic on 4k and retain solid 60fps with no stutters

Kudos and my eternal thanks to PhilS13 at the AC Forums who posted this solution over a year ago, just wish I'd found it sooner.

 

[RasmusP]

I'm playing on a 60hz screen with no freesync. There is definitely no tearing whatsoever. I'm someone who cannot stand any tearing, it drives me nuts. I did have to lower some graphic settings to keep my framerate steady and avoid the tearing from fluctuations.

Then you definitely have some syncing going on. 58 fps at 60 hz can still be vsync'ed but it will have some mild microstuttering every now and then.

I'll explain why this is technically 100% sure the case in the next quote.

It is my understanding that keeping the framerate steady, with no jumps, and not exceeding the refresh rate of the monitor, would prevent tearing.

No, that's sadly completely incorrect. But it's not easy to find a good explanation for this so 2 years ago, I had no clue either...

So it works like this:
Your monitor is constantly, line for line, refreshing the visible image.
You have 60 hz, so your refresh takes 16.67ms, going either from bottom to the top or from top to bottom (it's one of it, not both. Depending on the monitor).

The pixels in a normal, standard flat screen are crystals that are moved by voltage, with the backlight always on.

So a crystal gets a new input every 16.67ms and will stay in its position between the inputs.
This is important! With old crt monitors, the frame was only visible for a very short time! (flickering if you're sensitive for it, so many had 100 hz instead of 60).

Now the gpu puts one frame into the buffer with 58 fps. That means every 17.24ms.

The monitor will grab that frame every 16.67ms and will start to refresh the crystals line after line.

You can see that this is not synced so at one point of this refresh, you'll get the new frame inserted into the frame buffer and the monitor will continue the refresh with the new frame.
That generates the tearing border.

However, since the gpu puts new frames slower into the buffer than the monitor refreshes, you won't have a tearing border in every frame!
If you would push 300 fps into a 60 hz monitor buffer, you would have 5 tearing borders visible per refresh cycle.

I had to play one game without vsync on a 60 hz monitor since I could only reach an average of 55 fps.
I found that 47 fps was a good value for limiting, since the tearing border didn't appear in every refresh cycle and always was in a different height of the monitor.
That was bearable for me, although stuttering a bit.. But at least a constant stutter that you could get used to.


Now about syncing:
With vsync, the gpu will wait for the monitor to start a new refresh cycle, which needs 1-3 frames to work, since the gpu needs to keep at least one frame ready to push into the frame buffer, when the monitor is ready.
This leads to the famous input lag with vsync.

If your fps drop below 60 fps with 60 hz and vsync, the monitor will display the current frame a second time (or 3rd if your fps drop a lot).
This leads to stuttering.

With freesync/gsync, the monitor will wait for the gpu to get the frame ready. So you won't have tearing and also don't need any buffering.
Which is why freesync and gsync always have low input lag.

 

[william nolen]

What sort of stuttering do you have? Does it only happen during the day to night transitions?

The stuttering I had was during turning, basically anytime the horizon was shifting at a quick pace. It wasn't related to the weather or time of day.

 

[william nolen]

Then you definitely have some syncing going on. 58 fps at 60 hz can still be vsync'ed but it will have some mild microstuttering every now and then.

I'll explain why this is technically 100% sure the case in the next quote.

No, that's sadly completely incorrect. But it's not easy to find a good explanation for this so 2 years ago, I had no clue either...

So it works like this:
Your monitor is constantly, line for line, refreshing the visible image.
You have 60 hz, so your refresh takes 16.67ms, going either from bottom to the top or from top to bottom (it's one of it, not both. Depending on the monitor).

The pixels in a normal, standard flat screen are crystals that are moved by voltage, with the backlight always on.

So a crystal gets a new input every 16.67ms and will stay in its position between the inputs.
This is important! With old crt monitors, the frame was only visible for a very short time! (flickering if you're sensitive for it, so many had 100 hz instead of 60).

Now the gpu puts one frame into the buffer with 58 fps. That means every 17.24ms.

The monitor will grab that frame every 16.67ms and will start to refresh the crystals line after line.

You can see that this is not synced so at one point of this refresh, you'll get the new frame inserted into the frame buffer and the monitor will continue the refresh with the new frame.
That generates the tearing border.

However, since the gpu puts new frames slower into the buffer than the monitor refreshes, you won't have a tearing border in every frame!
If you would push 300 fps into a 60 hz monitor buffer, you would have 5 tearing borders visible per refresh cycle.

I had to play one game without vsync on a 60 hz monitor since I could only reach an average of 55 fps.
I found that 47 fps was a good value for limiting, since the tearing border didn't appear in every refresh cycle and always was in a different height of the monitor.
That was bearable for me, although stuttering a bit.. But at least a constant stutter that you could get used to.


Now about syncing:
With vsync, the gpu will wait for the monitor to start a new refresh cycle, which needs 1-3 frames to work, since the gpu needs to keep at least one frame ready to push into the frame buffer, when the monitor is ready.
This leads to the famous input lag with vsync.

If your fps drop below 60 fps with 60 hz and vsync, the monitor will display the current frame a second time (or 3rd if your fps drop a lot).
This leads to stuttering.

With freesync/gsync, the monitor will wait for the gpu to get the frame ready. So you won't have tearing and also don't need any buffering.
Which is why freesync and gsync always have low input lag.

What you're saying makes sense. It sounds like I've been misinformed on how some (or much) of this stuff works.

The stuttering in ACC, at least for my machine, was completely related to HLOD being on. I actually got the idea to try changing that from another post I saw on the Steam forums, and it worked for me. With HLOD, there is a tiny millisecond stutter basically anytime I turn on track, even slightly. Luckily now, the game is perfectly smooth. Now if I could just buy a new video card so I could ramp up the resolution and settings! lol

In regards to the tearing, I didn't get a chance to play last night, but I am hoping to have time to log on a bit this evening. I know for a fact I have v-sync off in game and Radeon settings, but what I am not 100% of is if I am in exclusive fullscreen or window borderless. If I'm in borderless, then that may explain the lack of tearing since i'm getting the windows v-sync, and if that's the case I want to switch to exclusive and see how it reacts. I appreciate the detailed explanation, it's quite informative.

 

[william nolen]

What you're saying makes sense. It sounds like I've been misinformed on how some (or much) of this stuff works.

The stuttering in ACC, at least for my machine, was completely related to HLOD being on. I actually got the idea to try changing that from another post I saw on the Steam forums, and it worked for me. With HLOD, there is a tiny millisecond stutter basically anytime I turn on track, even slightly. Luckily now, the game is perfectly smooth. Now if I could just buy a new video card so I could ramp up the resolution and settings! lol

In regards to the tearing, I didn't get a chance to play last night, but I am hoping to have time to log on a bit this evening. I know for a fact I have v-sync off in game and Radeon settings, but what I am not 100% of is if I am in exclusive fullscreen or window borderless. If I'm in borderless, then that may explain the lack of tearing since i'm getting the windows v-sync, and if that's the case I want to switch to exclusive and see how it reacts. I appreciate the detailed explanation, it's quite informative.

You were right, I have exclusive fullscreen off. When enabled I do have some slight tearing, mostly in the skyline. It's not bad, but it's enough to annoy me. No stuttering, but I'll stick to borderless window for now. I should have purchased a freesync tv lol.

When enabling hlod, I do still get the stutters in both modes, so hopefully that helps some folks having issues.

 

[RasmusP]

You were right, I have exclusive fullscreen off. When enabled I do have some slight tearing, mostly in the skyline. It's not bad, but it's enough to annoy me. No stuttering, but I'll stick to borderless window for now. I should have purchased a freesync tv lol.

When enabling hlod, I do still get the stutters in both modes, so hopefully that helps some folks having issues.

Nice to hear that we're both not imagining things

I don't have issues with hlod but I can imagine that some "special" LOD'ing can create frametime issues. So thanks for that!

 

[Chris Bloom]

Thank you. This has helped significantly.

 

[Douw Gerber]

Hi all

Also started getting this stutter every few seconds. Tried most of the suggestions in this thread which did seem to help to reduce the severity of the stutter but it was still there.

It was never a problem before yesterday. What did I change?

I had disabled my Dell 24" screen while I was in my rig (LG 34" UltraWide used here) while in ACC.

I can now confirm that when I enable my Dell screen the stutters are no longer there.

 

[jbt308]

After trying all suggestions, I was able to fix by changing from full screen to windowed mode. I5, 3080ti, 16g, triple 1440s. Able to run epic @ 70+ fps with 35 ai cars, no stutters, i almost cried.

 

[RasmusP]

After trying all suggestions, I was able to fix by changing from full screen to windowed mode. I5, 3080ti, 16g, triple 1440s. Able to run epic @ 70+ fps with 35 ai cars, no stutters, i almost cried.

Happy for your success but that doesn't make any sense to be honest.
However there are a few things that are different between full screen or windowed:
- fullscreen optimizations might be buggy for you. Right click on the ac2-win-shipping or something like that exe and disable them

- borderless sometimes activates the vsync from Windows desktop manager. Game might report 70 fps but you're simply running vsync.

- full screen might enable gsync/freesync and if that's bugged somehow, you can get some stuttering etc

 

[jbt308]

Happy for your success but that doesn't make any sense to be honest.
However there are a few things that are different between full screen or windowed:
- fullscreen optimizations might be buggy for you. Right click on the ac2-win-shipping or something like that exe and disable them

- borderless sometimes activates the vsync from Windows desktop manager. Game might report 70 fps but you're simply running vsync.

- full screen might enable gsync/freesync and if that's bugged somehow, you can get some stuttering etc

No I hear you, and it seems like I may have spoken too soon, stutter is back today. At this point, im going to totally wipe the pc and start from scratch. I received this pc as part of a purchase from a friend, so with all thr upgrades, I should be getting better performance. At this point aclean wipe I think is my only real option.

Oh, and to some of the points you brought up. Tried disabling the optimization, didn't work, turned gsync on/off, no change. And the same for vsync.

I can get the game running at 100+ fps, and it will drop 30-50 fps every few seconds, no matter what the graphic settings. Its very odd.

 

[RasmusP]

At this point aclean wipe I think is my only real option

Yeah maybe that's quicker than tinkering without success
I sadly have no further clue, sorry!

Apart from overheating or something starting in the background and killing your performance...

 

[Barman1965]

Running 4 monitors, 3 for triple screens and a 4th for telemetry etc. Been using simple runtime for the stretch but decided today to try nvidea surround. This deactivated my 4th screen so went back to simple runtime but 4th monitor still not working. Decided to just leave it and try a few laps in acc. Got a irritating stutter which is how I ended up here. Tried all the tricks mentioned but it wouldn't improve. Even running ultra low settings the stutter was always there. Read somewhere here someone had issues till they reconnected their 4th screen. Couldn't get it going till I realised I had to extend the screens in display settings. Once I had that screen going, all stutters gone. Strange but true. Thanks to whomever posted that.

 

[Oubaas]

Thanks for sharing this, @MapoUK. This works for VR. I was about to give up on this title. It looked awful and stuttered horribly.

I followed your instructions, disabled Game Bar, disabled Full Screen Optimizations on the executable, launched the sim, chose the, "Epic" preset, enabled V-Sync, and set max frame rate to 143, one below what my monitor runs.

Then I put on my Oculus Rift S and drove. It's now as clear and smooth as Automobilista or Project Cars in VR, first rate! Thanks for sharing this!

 

[Piolo83]

I solved it with the following procedure: provided that a cpu amd ryzen 7 5800x, rx 6800xt, 32gb ram ddr4 3600, 32 inch 2k 144hz screen, I disabled hpet (high precision event timer), from device manager ,then uninstalled ryzen master which automatically re-enabled hpet. To avoid further enabling I opened the command prompt window and typed bcdedit /set useplatformclock false (to reactivate it do the same procedure and insert "true" in the command line), waited for it to be deactivated and restarted the pc. And by magic everything was perfect even with more than 40 cars on the grid and video settings on ultra.

 

[BB Litefoot]

yes i found this helpful i was only having slite micro on sharp bends nothing non playable n after upping dlss to quality {which is hardly noticible from Balance.) i now get micro freeze in those places tho after reading about the hlod effect il try again on Quality with hlod off.. anyhow Dlss Balance is really smooth now even with hlod on., like u id gone without playing for months on my triples then got the the same trouble after never having it before so was a total head scratcher for me as to why i was getting issues!., anyhow seems all sorted now!!

 

[SwannyUK]

After never having ACC run without stuttering, and returning after buying the GT4 pack I was determined to try and resolve the issue. I was running at 80 to 120 fps in 4k but was still plagued with the dreaded microstutters.

Most of you may already know this, but for those who it may help.

To resolve the issue (for me anyway) if you locate the file ac2-win64-shipping.exe (which in located in your ACC game folder SteamLibrary\steamapps\common\Assetto Corsa Competizione\AC2\Binaries\Win64) - right click on it, select properties, select the compatibility tab and click on Disable Full Screen Optimisations. In game set the frame limiter to your screen refresh rate and turn on V-Sync. Windows Game Bar Mode also needs to be disabled for this to work.

I also used the same same option on the acc.exe file (which in located in your ACC game folder SteamLibrary\steamapps\common\Assetto Corsa Competizione\AC2) just in case.

It's cured my microstutters and I've been able to put most settings back to epic on 4k and retain solid 60fps with no stutters

Kudos and my eternal thanks to PhilS13 at the AC Forums who posted this solution over a year ago, just wish I'd found it sooner.

Many thanks for this - my ACC has been crap lately with this stuttering. Did as you said (other than vsync) as well as HLOD off and all is well again.

 

[Frans van der Linden]

Seems to have improved. Not fixed yet. Thanks for your pointers.

I had a lot of (micro) stutters. Turned out to be a overlay from discord causing this issue.
Don't know if you run any overlays. Turn them off for beginning would be my advice!

 

[the__dewd]

You're a dead set legend! Problemo solved!

 

[Teotihuacan_13]

Hello the addicts of the steering wheel,
I took ACC on steam and at my great despair, whatever the graphic settings there were micros lag, visible enough to ruin my gaming experience. After trying all the manipulation of this forum and pulling my hair, none of it worked for me...
and then miracle I realized that once my Thrustmaster TSPC racer 488 steering wheel disconnected it became so smooth and fluid like the skin of my first childhood love. I said I will have to be a gamepad gamer!!!
And I realized that my TSPC racer was configured on ADVANCED for what knows, I went back to basic configuration and miracle plus a single lag...
I Guess This stuttering problem can’t be about everything but if it can help some of you it would be genial.
thanks for the help guys