Stutters above Caucasus forests in Pimax Super UW

[Katmandu]

My system is 9800x3d, 64gb, 5090, win11. I get stable 90fps when low flying above *normal* land with a few trees, villages, etc. Once I low fly over some forests, my frametime turns into a saw and i get constant stutters. No issues on 4k flat screen of course.

Flat screen over forests:

VR over forests (bad graphics appearance due to quad views):

VR over normal land with some trees and buildings (solid 90fps, the solitary spike is due to screenshot):

What can be done is the question! Could it be Pimax headtracking sapping the CPU? I attach the mission file, forrests are straight ahead, "normal" landscape below.

F15C vs MiG-31.miz

Edited 10 hours ago by Katmandu

[MadMonty]

Try limiting FPS in DCS to 120, other values caused micro stutters in my case. If it doesn‘t help, try other values. DCS FPS does have an impact on micro stutters…

[Pteradon]

Thanks @MadMonty

I have the same experience as @Katmandu in the Caucasus. (Flying low in a valley with forest.)

i thought it was caused by the new update (few weeks back) wich also updated the Caucasus map a bit visual.

Would be nice to fly low through the valley without stutters.

I was also thinking about using Process Lasso.

 

[Picchio]

I'm sure you have already figured it out but forests in general really bring frametimes up in VR, no matter the map. You can lower Forest Visibility (together with your Shadows settings) but don't expect too much of an improvement.

[WipeUout]

The 22 October did increase frametime for me in my test (FA-18, Caucasus).  At first, I though it was related to the visor introduced but I am seeing this increased frametime with all my airplanes by 0,7 to 1 ms.  Flying over high density of map objects, such as trees, always caused frametime spikes but it is now more apparent unless I reduce my settings.

Using process lasso will certainly help with the random CPU cycle stealing from other programs running in the background and causing stutters but don't expect it will create headroom unless you have something constantly running in the background.  The only three ways to regain headroom is lower setting, upgrade hardware or wait for an optimized/improved changed to software. 

Hopefully the next patch will give us back some headroom.

[Indyplumber]

Funny, i noticed this last night flying over forest on Syria.  Was planning on doing some settings tweaks tonight to see if I can smooth it out.  I do not use quadviews (pimax or mbuch) as I find it looks horrible with either one.  I'm using just Piplay latest and tweaking in there and DCS settings.  I get 60+ fps pretty consistently with piplay set to medium resolution.

 

Does the motion smoothing in Nvidia app and Piplay have anything to do with this?

[Dawgboy]

15 minutes ago, Indyplumber said:

Funny, i noticed this last night flying over forest on Syria.  Was planning on doing some settings tweaks tonight to see if I can smooth it out.  I do not use quadviews (pimax or mbuch) as I find it looks horrible with either one.  I'm using just Piplay latest and tweaking in there and DCS settings.  I get 60+ fps pretty consistently with piplay set to medium resolution.

 

Does the motion smoothing in Nvidia app and Piplay have anything to do with this?

Same...no QV. Please, what are your setting details in PP and DCS, if you don't mind? TIA. I'm just starting my DCS quest with Super U/W 50ppd. 

[Katmandu]

It's not just Caucasus and it's not just forests I now find. Circling the same patch of desert in Nevada leads to stutters  over some patches of terrain, but not the others. This is far away from Vegas, near Groom Lake. The graph is always showing CPU bound, so it does not seem to be related to the resolution of the headset, but to something else that hammers the CPU.

I am using Quad Views, the stutters are identical with stock PimaxPlay and Mbucchia. My system is 9800x3d, 64gb, 5090, win11.

Quote

The 22 October did increase frametime for me in my test (FA-18, Caucasus).

I've got two different version of DCS, the current latest one and the April 2025 2.9.13 version - the stutters are near identical.

Edited yesterday at 09:33 PM by Katmandu

[WipeUout]

1 hour ago, Katmandu said:

I am using Quad Views, the stutters are identical with stock PimaxPlay and Mbucchia. My system is 9800x3d, 64gb, 5090, win11.

That's weird.  I flew my FA-18C on Nevada map in a similar fashion and my GPU frametime is between 8.3 and 9.2 ms, no stutters whatsoever.  The 8kX has only about half the pixels rendered compared to the Crystal Super but if you are using DFR, you should get decent frametime, certainly lower than 11 ms.  This has to be related to settings or something running in the background.  Did you tried installing process lasso?  It will show what's running in parallel with DCS and you may find the culprit there.

Edited yesterday at 11:01 PM by WipeUout
Typo

[Katmandu]

13 hours ago, WipeUout said:

8kX

Could it be down to the 8KX using Valve base stations and thus more efficient tracking algos that don't tax the CPU quite as much?

E.g., in their own testing Pimax found that the OG Crystal vastly outperformed Crystal Light even when NOT using eye tracking/DFR in DCS. Crystal Light does its tracking on the CPU, while the OG Crystal uses its stand alone snapdragon chipset to do the tracking. (Going forward, this forms a good argument for standalone headsets like the OG as their own CPU will be doing the head AND eye tracking calculations.)

@13:45

Quote

Did you tried installing process lasso?  It will show what's running in parallel with DCS and you may find the culprit there.

I have it installed, will need to play around with it as I've never used it before.

Quote

Try limiting FPS in DCS to 120, other values caused micro stutters in my case.

In my case, the best limit is 90fps. Set at 120 I get saw like frametime even when flying over non-forested terrain.

Edited 10 hours ago by Katmandu

[WipeUout]

7 hours ago, Katmandu said:

Could it be down to the 8KX using Valve base stations and thus more efficient tracking algos that don't tax the CPU quite as much?

Entirely possible that lighthouse position tracking compared to SLAM may have a different performance cost.  Someone with the crystal lighthouse faceplate could test that.

7 hours ago, Katmandu said:

In my case, the best limit is 90fps. Set at 120 I get saw like frametime even when flying over non-forested terrain.

Limiting FPS in DCS has to be slightly above the refresh rate in my case or I get stutters.  DCS output varies between 89 and 91 FPS very briefly but enough to cause stutters.  My FPS cap in DCS is set at 95 because of that.