Only in our dreams 
Yep, same and only working solution ever since the simās release.
Came to say this. A core doesnāt have to be pegged for a thread to be waiting on other threads to do their things.
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It doesnāt, but a pegged (heh, music term) core was pretty common in SU8.
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After testing last night, I think I have a configuration that works for me!
And it seems like the cloud update in SU9 was adding to my system stress, so I first had to calibrate around them to get the cloud fidelity I wanted. I am a sucker for good clouds, even on my slow machine. Clouds are so much of what you see at any time.
But now, finally, I am getting better performance AND better fidelity than I was during SU8.
And I am pretty sure my, āHammeredā main thread was having to deal too much with clouds on top of everything else at a major airport near photogrammetry.
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100% agree clouds have a far bigger impact that they used to - they seem higher fidelity that in SU8 which means they look better but they push the CPU more.
Best to configure the system with full clouds to get the best performance in any given situation
I was experimenting around with locking FPS last night. I run a 144hz monitor (Predator) which for MFS I turn down to 60hz
I used to only lock FPS (30) through Vsync in the Sim but last night I locked FPS (to 30) through Nvidia and kept it locked in the Sim (30) through Vsycnc which resulted in a much smoother experience for me. I read previously you should only lock one and not both?
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Thatās interesting that clouds are now affecting the main thread. Has this been the case all along? I thought the clouds and weather mainly affected GPU performance.
If you donāt mind sharing, was it reducing TLOD that has helped you re-calibrate your system? Or did you have to change other settings as well?
With my slower computer some things impact my performance more than they would someone else.
Clouds have always impacted GPU and CPU, GPU moreā¦ but High and especially Ultra still noticeably tax the CPU Main Thread and I suspect they impact my Main Thread more now than before. But they look better so it is understandable.
My settings ended up being so similar after reconfiguring. While AFK, I really canāt tell you what changed, I think I sacrificed some traffic, but it was a lot of tweaking in Dev Mode while starting at my favorite busy airport then flying a favorite short route into a desolate area and landing at a small town air strip.
I can confirm that the performance in SU9 beta is not better than SU8. Even worse.
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because the clouds are higher fidelity - need to adjust some settings to get it running smooth - either change cloud quality or adjust TLOD
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Iāve been following this thread for a few days and trying to validate what everyone else is seeing. In my experience, the main thread getting hammered seems to be mostly due to PG regions. When Iām flying in areas that are not-PG, or close to PG areas, Iād say my performance is on par with SU8. I tried to adjust my TLOD sliders down (I typically run at 150), but even at 50 or 100 thereās no change to the hammering my CPU is getting. I know you might say āwell itās something elseā, but Iāve turned off all traffic and anything Iāve ever read as being high-CPU impacting.
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My theory is similar but more involved.
It isnāt exactly photogrammetry. But photogrammetry adds load to the main thread.
It isnāt exactly traffic, traffic just adds load to your main thread.
It isnāt exactly bespoke airports, they just add to the main threadās load.
It isnāt exactly TLODā¦ etc.
It can be easy to blame one thing, especially since removing one thing can really seem to helpā¦ but I suspect it is the worst when the Main Thread is handling ALL the taxing things it could possibly handle at once.
For me, that seems to be just after wheels up just above (like under 1,000 feet) a big, busy airport in a photogrammetry area.
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Could it be the playback of some sounds being processed on the main thread? Because I notice that even reducing the graphics settings to zeroā¦ the stuttering occurs. I was wondering if they did this since SU8 when they implemented the sound devices to be selected in the SOUND tab.
I think that, because today I dedicated myself to looking in detail at each of the graphic attributes, testing all possible combinations between LOW, MEDIUM, HIGH and ULTRAā¦ and the stutter is always the same, in my case.
Iām not overclocking anything in my system either the CPU or the GPU. Updated bios, latest chipset drivers and video card. R5 3600x / RX5700XT / 32G DDR4 3000mhz
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This is where the sound processing comes to my mind, because when the aricrafts accelerate, some sounds come in stronger, such as the sound of the wind, creaking noises and that these would not be well coded in terms of their reproduction, on main Thread.
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Apparently, the way is to wait. But if anyone can observe these sounds that Iāve talked about, you will have the perception whenthey occur, comes the stutterings.
We move on analyzing!
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I will keep my ears open.
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Well said and I honestly think this is the best way this problem has been put thus far.
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It might help raise awareness if people can mark this as ānot fixedā hereā¦
https://forums.flightsimulator.com/t/4-ongoing-performance-optimization-work/509675
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If my memory serves me right, the team said that new clouds were being introduced into SU9, so this is most likely the cause. Try disabling atmospheric effects from within the dev menu.
Itās possible but I think it unlikely.
The issue is at itās worst on the ground and itās the same with clear skies as it is with overcast. Once up in the air flying through the clouds themselves things are just fine, at least for me.
When a 3090 exists it cannot be right that on the ground the only way to load a 2080ti up to 100% and make the game GPU limited is to max everything out and turn the render scaling up beyond 4K.
The game is very heavily CPU limited in almost every scenario. This time last year this wasnāt the case.
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I got the feeling this and interior window reflection flickering on renderscale <100 have somehow to do with the cockpit display refresh rate. I had it set to āhighā and switched to āmediumā.
Performance now is good but the window reflections on the inside donāt flicker in my case anymore, instead they are gone when camera is steady.
Visually I donāt see any big change on the display refresh cycles so maybe there is something broken or interfering?
Could someone else test this? 
Not quite true.
The simplest workaround is limiting FPS to 30. It doesnāt matter what is limiting you if you reserve enough milliseconds per cycle for all computations to be run.
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