This could be on your system but on mine, I don’t have a problem of “limited by main thread”. All cores can be at ~30% utilization and memory at 50% but the slideshows still happen randomly. This massive slowdown can happen while flying in the middle of nowhere with nothing but flat terrain around for hundreds of miles. I personally do think there is a memory leak (or poor memory management) in this sim and saving and restarting the flight resets the memory stack.
[quote=“Buddywoof3669, post:11, topic:412551”]
All cores can be at ~30% utilization and memory at 50% but the slideshows still happen randomly.
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Computers do not operate randomly unless deliberately programmed to do so. There has to be a reason for your slideshows other than random MSFS code execution. (Not to be confused with MSFS programmed to allow flying randomly to anywhere at any time.)
You assume that MSFS is processing or should only be processing what you are seeing. I have parked in front of a blank concrete wall at an airport with nothing visibly moving. But my FPS drops to below 12 FPS! Why is a blank wall slowing down my system? Should my FPS be like 100 for a blank wall? Examining what MSFS is doing reveals that MSFS using Superman’s X-ray vision to look through the wall to render everything at the airport, ground crew, parked and moving aircraft, airport vehicles, airport buildings. In addition, since my graphics settings are very high, it is rendering these objects at a very high level of detail. No wonder why my FPS is cratering! MSFS may be designed poorly because it is trying to process objects I cannot see. But for right now, it is what it is.
The definition of a memory leak (for programmers) is an error condition that happens to everyone and the only workaround is to restart the system to clear the corrupted memory. For some reason users with many different hardware configurations aren’t seeing any slideshow slowdowns.
I agree that the problem is poor memory management. MSFS is gathering more graphic information faster than it can process. It can only put that information into memory until it is processed. MSFS cannot free up memory until the graphics information is processed. MSFS should be coded correctly to process graphics information faster than it is received. Or the amount of graphics information requested should be limited according to CPU processing capacity. Or the CPU can be upgraded or overclocked to process graphics faster. Or memory can be added to provide additional room to temporarily store graphics information.
I experienced this problem yesterday, for the first time. I was en route with my CRJ at FL240, flying in VR. At some point, I was entering a high cloud layer without much structure, but a marked reduction of visibility. Frame rates dropped to 5 or 6, almost unflyable, and any head movement made things even worse.
Things went back to normal once I descended below that misty cloud layer.
I have clouds set to ultra. I have experienced a certain drop in frame rates before, when the sim had to render many cloud layers, with impressive looking cumulus. But the sim remained flyable.
My question is: why does the sim struggle so much with mist (which in essence is just a reduction of visibility)?
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No idea to your question . But i will test with high settings for the clouds instead of ultra
Can also confirm FPS drop in high altitude clouds since last update. Never had those issues (only FPS drops nearby big airports but that is another story) before latest update and always played on ultra settings like now.
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Can also confirm, random slideshow moments at high altitudes passing through clouds.
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same for me- severe fps issue / lower fps with a 3090 in higher cloud layers.
MODERATOR EDIT: Removed ping to Asobo.
Please do not ping team members to bring attention to an issue or bug.
Same here:
RTX3080ti
Lowering resolution doesn’t help so it doesn’t seem to be graphics related.
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I have the issue as well. The very high clouds ( FL350+) cause severe fps drops.
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Same problem !
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Kinda glad it’s not just me. FPS will drop from say 35 to 20 and very choppy with ultra setting. Each setting of clouds will gain about 2.5 - 5 fps. This is for the high level mist and also low level heavy rain and overcast. Big fluffy clouds that look great do not do this. I’ve tried turning off icing to to see if that had an impact but it didn’t.
5950x
3090
64gb
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Yes absolutely the same for me with high class system 3090 10900k 5.0 ghz. 
high mist, fog and high stratus or cirrus clouds huge fps drop
MODERATOR EDIT: Removed ping to Asobo.
Please do not ping team members to bring attention to an issue or bug.
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I had the same with my rtx 3080 and 10700kf. Climbing through low clouds near KSFO brought my fps down to the mid 20s and caused stutters. Also had it at high altitude over the alps. Seems very dependent on cloud type being displayed.
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It does still appear to be an issue with performance impacts inside certain cloud / fog depiction layers. Just tested in DX12 and the drop still occurs:
Inside translucent cloud layer:
And just outside:
Are they on ultra?
They are. Only occurs when you are inside the layer (this could even be a single cloud layer as per the original video from the OP).
For comparison, flying outside / under a dense cloud depiction (also at ultra) has no impact on performance:
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Yep, exactly the same here on Ultra (RTX3080/11900K/VR). The moment you dip INTO that sort of cloud layer… boom, instant Frame rate drop. You can be utterly surrounded by clouds of any depth at Ultra with great frame rates, but the moment you slightly enter this sort of cloud layer… chug chug.
I am going to give “high” a go tonight and see if that helps much and whether it degrades the visuals much.
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I have the same issue. Both high and low altitude, only certain types of fog/cloud will bring the simulation to a slide show. RTX3080 and i7 12th gen. Performance is great everywhere else except for in these very specific cloud layers.
Taking volumetric cloud setting to high-end fixes it, but I prefer to keep on ultra as it makes clouds look so much better the rest of the time.
I’m using DX11 still as well.
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