All,

I've been using P3Dv4 on and off for several months now; but I keep running into this same performance issue that really has me stumped.  My system is a "middle of the road" 4790K oc'd to 4.6 with a GTX 1070, 16GB RAM, using a single 39" 1080P screen.  I'm not a slider junkie: Autogen is about 75%, no dynamic lights, 4X SSAA, etc. (in short, I don't mind sacrificing some of the bells and whistles for frames).  Monitor refresh is set to 30Hz, with Vsync On/Triple Buffering, and frames locked in the the sim at 30 fps.

In situations where I can maintain 30 fps, P3D is silky smooth - no micro-stutters, long frames, or any other problems.  Performance is perfect.  However, as soon as the frame rate dips below the monitor refresh rate, the sim turns into a stuttering mess.  I've been simming for over 30 years and I fully expect frame rates to suffer when flying into complex scenery with heavy AI traffic; but this is different.  On FSX, as the frames decrease, the difference is noticeable but the frames stay consistent (a lot of times I don't even notice the frames dropping until they get into the low twenties.  On P3D, falling just a couple of fps below 30 results in obvious jerks and stutters... I may be exaggerating slightly; but 25-28 fps in Prepar3D feels more like 12-15 fps in FSX.

Do others experience this issue, or is it just me?  I've experimented with some of the more common tweaks (FFTF, Affinity Mask, setting internal frames to unlimited, etc.); but they appear to have no impact.  My gut feeling is that the adaptive vsync of Windows Desktop composition may be the culprit; but I don't know of any way to tweak that.  Any suggestions would be appreciated.

Yep. I think its a common problem with TV's and going below VSYNC and the refreshrate of your choice. 

I have the refreshrate at 25HZ VSYNC on but unlimited FPS and butter smooth as long as it doesnt dip to 23-24.

 

Thanks Michael Moe 

Thanks for the response Michael.  If that's the case, I'm really surprised there hasn't been more backlash on this subject since it is virtually impossible to tune every combination of third party aircraft, AI, and scenery package to maintain a minimum frame/refresh rate... especially as add-ons get more and more complex without a VAS limitation.  Do folks really just silently endure the jerkiness when the frames drop?  Knowing these forums as I do, I find that hard to believe.  I guess a G sync monitor might address the problem; but right now they're too small and expensive for me to take seriously.

I dont know what else to say other than i am in the same boat and you are right. 

Even 40-50fps with no VSYNC and refreshrate at 60 or 59hz doesnt feel as smooth as my setup in the post before. 

This was  never the case in FSX where i always was using no VSYNC/1080p.

Now its 49"4K/25HZ VSYNC and unlimited fps and much smoother than anything before. (above 25)

Thanks Michael Moe 

 

On 10/18/2017 at 2:41 AM, MadDog said:

Monitor refresh is set to 30Hz, with Vsync On/Triple Buffering, and frames locked in the the sim at 30 fps.

What's it like with Vsync On/Triple Buffering and unlimited frame rate?

That x4 SSAA is probably killing your frame rate but still, with your system and only driving one 1080 screen, I would of expected frames potentially closer to 60 than 30. (Unlimited or 60Hz refresh rate set)

gb.

1 hour ago, gboz said:

with your system and only driving one 1080 screen, I would of expected frames potentially closer to 60 than 30. (Unlimited or 60Hz refresh rate set)

Yes, using Unlimited, I can approach or exceed 60 fps in less complex scenery; but I absolutely despise micro-stutters, so locking frames to 30 provides the best experience for me.  As I mentioned earlier, I'm very happy with performance at 30... the jerkiness only occurs when frames dip below 30.  If you can show me a system that can consistently maintain over 30 at a large airport (EGLL, EHAM, KATL, etc.), with a complex aircraft (TFDi, PMDG, FSLabs), full weather (Activesky) and AI Traffic, I would happily buy it.  I don't think 4x SSAA is the issue, I'm pretty sure the bottleneck is with the CPU and the current DWM vsync implementation.

Have you even tried using MSAA instead of SSAA? Also using lower res cloud textures and not to much cloud layers in ASP4 may help.

And don't forget: sliders in P3Dv4 in the same place like FSX means WAY higher settings, they don't translate 1:1!

21 minutes ago, MadDog said:

Yes, using Unlimited, I can approach or exceed 60 fps in less complex scenery; but I absolutely despise micro-stutters, so locking frames to 30 provides the best experience for me.  As I mentioned earlier, I'm very happy with performance at 30... the jerkiness only occurs when frames dip below 30.  If you can show me a system that can consistently maintain over 30 at a large airport (EGLL, EHAM, KATL, etc.), with a complex aircraft (TFDi, PMDG, FSLabs), full weather (Activesky) and AI Traffic, I would happily buy it.  I don't think 4x SSAA is the issue, I'm pretty sure the bottleneck is with the CPU and the current DWM vsync implementation.

I loaded up in the QOTS II last night at KSEA. I have a 7700k at 4.8ghz with a 1080ti and even though my FPS never dropped below 30 at 30hz I still had microstutters.

Any chance this started after you installed FSLABS?

1 hour ago, akabam said:

Any chance this started after you installed FSLABS?

Nope, no FSLabs A320 here.  I need to get the sim running smoother with "lesser" aircraft before I try to introduce that beast . (I do use the A320 in FSX though).

2 hours ago, JoeFackel said:

Have you even tried using MSAA instead of SSAA? Also using lower res cloud textures and not to much cloud layers in ASP4 may help.

And don't forget: sliders in P3Dv4 in the same place like FSX means WAY higher settings, they don't translate 1:1!

I think some are missing the point of my post.  I know how to turn down settings to maintain performance. Heck, if I dumb down P3D to look like FS9, I could probably keep my refresh at 60 Hz and make >60 fps my target... but I didn't purchase P3D to look like FS9 (or even FSX).  For me, 30 fps has always provided the best compromise of visuals and performance... and, while not ideal, frames down in the high teens can be acceptable as long as stutters are avoided.

With just about any other sim (FSX, X-Plane, FSW, etc.), when the frames dip below 30, the rendering gets choppy... but it is more of a constant chop.  With P3D, the rendering below 30 fps is not constant at all... I'll get really long frames mixed in with shorter ones.  There is no rhythm... to use a musical term, it's syncopated (and not in a pleasing way).  If I could figure out a way to smooth out those stutters at lower frame rates, I'll finally be happy with P3D.

I'm guessing you've tried turning vsync and triple buffering off.

I run a 4K monitor at 60hz with no tb and no vsync and don't get the stutters. I do lock at 20 though and have most sliders at max.

 

Vic

9 minutes ago, vgbaron said:

I'm guessing you've tried turning vsync and triple buffering off.

I run a 4K monitor at 60hz with no tb and no vsync and don't get the stutters. I do lock at 20 though and have most sliders at max.

 

Vic

Similar here, 4K 60 Hz  no buffering or vsync and locked at 24.  OP dismissed SSAA, which I think should at least try it.  There is no discernible difference between SSAA and MSAA on a 4K screen.

26 minutes ago, downscc said:

Similar here, 4K 60 Hz  no buffering or vsync and locked at 24.  OP dismissed SSAA, which I think should at least try it.  There is no discernible difference between SSAA and MSAA on a 4K screen.

I haven't dismissed it, just have my doubts and haven't had a chance to try without it yet.  I will say that the difference between SSAA and MSAA is very discernible at 1080P and, even if it works, it would really only be a last resort (would probably force me to buy a 4K screen :)).  I have tried disabling vsync/tb; but it had no noticeable effect (I really think those checkboxes are somewhat misleading since vsync is always provided by Aero/DWM whether the boxes are checked or not).  Have not tried locking at 24 or 20 yet... will give it a try later; but doesn't it create microstutters at 60Hz?

By the way, I love your Logedit app... I've faithfully maintained my logbook since FS95 and your program has proven invaluable.  Not sure if you're aware; but it also appears to work for FSW (I think DT has kept the original FSX logbook format).

Maddog I am the same, I need to maintain 30fps to have a smooth sim, if it dips a couple of FPS below it's a stuttering mess. So this is what I do. I get a hardware mointor like hwmonitor and have it running whilst I'm in the sim experimenting. I see where the bottle neck is, CPU or GPU. Then I adjust settings that effect the particular hardware device. For example if it's my CPU I turn down autogen ( I see that you use 75% thats huge and I can't maintain 30fps with autogen on 75% in big cities), I also don't use AI which is a CPU resource hog. If my GPU is reaching 100% load I turn down things like shadows, I turn off reflections and DL etc etc.

Also affinity mask is a must for me as it makes a subtle difference, but it all counts. I spend a couple of hours once trying a range of different AM settings to work out which had the smoothest feel and one setting for me came up trump's.

Also for payware airports I turn off things like vehicles and people flow etc. I use ASP4 and I use 1024 textures, 5 cloud layers ( I will turn layers down more if need be) and there is a setting there for overcast to use in performance rather that high quality.

In addition what I found to be a very very good investment was buying SSD's. That eliminated alot of my stutters due to quicker texture loading ( note it did not give me more FPS just a smoother experience). 

So all in all what I am saying is changing one setting may seem like it made hardly any difference but it all adds up to make it worth while in the end.

Good luck and don't give up!

On 10/17/2017 at 11:41 AM, MadDog said:

Monitor refresh is set to 30Hz, with Vsync On/Triple Buffering, and frames locked in the the sim at 30 fps

Maddog,

I'm curious why you lock 30 fps in the sim if you're using vsync. Doesn't vsync automatically limit fps to refresh rate?

It seems there is no magic answer...and I can guarantee, all the folks that say they're running a config. at 20, or 24, or 25, or 30 hz refresh with vsync and they never have this problem are either not being truthful, or they never fly a situation that takes fps below refresh rate, or they just aren't as picky. ANYTIME fps drops below refresh there will be stutters.

The issue that I see that causes this problem on my system, is when the cpu just can't keep up...when that happens, there will ALWAYS be stutters. It's so easy to configure settings that don't overtax the gpu, but finding a setting that doesn't SOMETIMES overtax cpu is an impossibility for me.