Main thread loads up more and more and doesn't recover

Bug Reporting Hub Install, Performance & Graphics
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480

Just carried out two hops tonight. EGLL → LSGG and the reverse. Addons used (FSLabs 321neo, Inibuilds EGLL, Digital Design LSGG, GSX, VPilot with FSLTL)

EGLL (Start-up) - Mainthread 19ms, RDR thread 7ms, Manipulators 10.5ms. ‘Real’ FPS 50.

LSGG (At gate) - Mainthread 24.6ms, RDR thread 9.4ms, Manipulators 15.5ms. ‘Real’ FPS 40.

LSGG (After-push) - Mainthread 32ms, RDR Thread 11.9ms, Manupulators 16.4ms. ‘Real’ FPS 35

Heathrow (At gate - return leg) - Mainthread 35ms, RDR Thread 8.6ms, Manipulators 19.9ms, ‘Real’ FPS 30.

Noted that Mainthread + manipulators dropepd by 5ms when mouse over development toolbar.

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481

Exactly same situation like in my tests.

482

Really hope this isn’t a wait for SU4, but a hotfix. For me and what I can see everyone else on this thread - it is completly game breaking!

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483

For me personally, I have a paid product what I cant use. Simple as that.

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484

Exactly, i’m just disapointed that something like this can pass QC. I would like to use the product that i paid for in the advertised way. After having spent so much money on 2024 native addons i am not going back to 2020.

485

But why people are reporting exactly that? Here are sevaral screenshots with low manipulators but high main thread.

If you are right, then it is easy. Just do not open menus and toolbar icons during the flight, and everything is fine. Unfortunately again people are reporting increasing mainthreads with just using the plane controls and nothing else.

That is definately not globally true. Here are several examples in the confiiming flights over several hours with turnarounds and WITHOUT increasing threadtimes.

So far nobody described in detail, when the threads are rising. Where did you see this behavior?

Today I did a testflight: A350, live weather (cloudy and rainy), all kind of traffic switched on, BATC and GSX. No increasing threads at all. So we can take weather and traffic from the list.

486

And GSX by using it via toolbar icon. No change in MT timings.

487

Yes, you are right. The GSX window does not increase the threads, as it was confirmed before.

488

So seems my problem is the windows menu bar, or at least made the problem worse. Not sure if that was this thread or not, but smooth flight, avoided the windows bar to see if that was the cause of the issue. Reached the stand, pressed the windows key FPS immediately tanked. This also includes if I type anything in the windows search bar

489

I have to agree, I don’t want to wait months to be able to sim again. This is a game breaker bug

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490

this is nuts :smiley: how is this even possible? look at fps and mainthread

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491

Happening here too. Performance just gradually drops over time. Alt +tab to bring another window into focus, then returning to the sim brings the performance back up temporarily, then it’s just rinse and repeat. Have they even acknowledged this at all?

492

Dear Microsoft / Asobo Team,

I am writing this as a concerned and long-time member of the MSFS community. After Sim Update 3, the majority of users are experiencing severe problems that greatly affect the simulator’s usability. It is disappointing and frankly embarrassing that this issue did not make it into the last Development Update on September 4, 2026. In fact, this week’s update contained almost no content at all, which raises the question: is this still due to vacation time, or what is going on?

Furthermore, I struggle to understand the role of the Community Managers. I would like to address this specifically with regard to the EU Community Manager. While I respect the fact that there may be a lot of unseen work happening in the background, it is difficult for the community to accept when a Community Manager streams on Twitch (albeit from a private account) and then dismisses every question about the ongoing issues by saying “this is a private stream and has nothing to do with MS/Asobo.” From a community perspective, this comes across as tone-deaf. The stream creates the impression that “everything is fine,” when in reality, it clearly is not.

This is not a minor inconvenience. Content creators, who rely on MSFS for their livelihood, are in some cases worried about their very existence because they cannot stream properly under these circumstances. Some are even openly considering switching to X-Plane 12 for the time being.

It is also frustrating that neither Asobo, Microsoft, nor the Community Managers actively engage in the forum threads to calm the situation. As long as there is no visible communication, frustration will continue to grow—and understandably so. Under the current circumstances, it is no surprise that other simulators are gaining significance.

We, as a community, strongly urge you to take this matter seriously and to communicate more transparently and proactively. The issues introduced with Sim Update 3 must be addressed with the highest priority.

Sincerely,
A concerned MSFS community member

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493

Tbf Chewwy responded here and assured us that the developers are aware of the problem and are working on it. He can’t say more than he is allowed to. But I understand the frustration 100%, as I am also affected by it. I guess there won’t be any kind of hotfix and we’ll have to try SU4 Beta, which will may fix this issue, but break other things, lol. We can only wait and hope that the problem will be resolved as soon as possible. I’m not going to waste my time trying out all these “solutions” that lead nowhere.

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494

I stopped simming in msfs24 since this bug reached final SU3.

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495

I have Mainthread issues right from the start which is why i haven’t even played enough to get even more degradation over time. The latency is already around 25-30ms and very soon after reaches 40-50ms. It doesn’t even matter if i change CPU heavy settings, it will always stay around 30 raw fps (no, i have no vsync or anything like that active) with the before mentioned latency.

I always do a full reinstall and clear any leftovers and or caches. I’ve never had any issues with the sim up until the SU3 live build. From the SU3 beta (didn’t try the last 2 beta builds) to the live version halved my fps and completely destroyed my mainthread.

I’m running the same settings as before which gave me 60 or more raw fps without any high latency or mainthread issues. I also tried t he gpu driver i used during the earlier beta builds.

9950X3D, 5090.

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496

Thank you for saying this. I’ve definitely been fooled by the placebo slop people post and had my system damaged as a result, ending in multiple fresh windows installs.

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497

So more testing I’ve found the same issues as above. Thought if I didn’t press the windows search bar that the problem wouldn’t show up, but it still eventually does. The windows search bar just immediately creates the problem. Mouse moved over the dev menu in sim also cleares the low FPS as shown in the video above. So.. Yeah. That basically parks the sim until the issue is solved by Asobo…… game breaking

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501

However, approaching EHRD with a turn over the photogrammetry city is unparalleled.

I can still do great flights with an hour flight time or so. I hardly ever fly longer. Does that also not work for you guys?

502

Hi everyone,
I hope this post can sweeten the weekend for some of you, because I think I’ve found a workaround (at least for my rig) that finally fixes the steadily increasing mainthread latency.

Important upfront: I’m only talking about the bug that’s mentioned in the title of this thread - not the one caused by opening and closing the controller settings.

As you can see from my previous posts here, I’ve already tried just about everything on the BIOS, CPU, GPU, Windows, and sim settings side, with no real success.

User RogueNaught1 reported that uninstalling his GPU drivers in Safe Mode with DDU and then reinstalling them fixed the issue for him. I tried exactly that, but unfortunately it didn’t work on my end.
However, in a later post he also mentioned reinstalling his sound drivers, which got me curious and led me to dig deeper into the audio side of things.

Here’s what I found:

  • My motherboard (Gigabyte B850 Aorus Elite) still had a Realtek audio driver from 2021 installed. On the Gigabyte support page I noticed there was a brand-new driver from late August this year. I updated to that version.

  • With the new driver installed, I had noticeably fewer mainthread spikes, but the creeping latency problem was still there. Still, that improvement was enough to make me keep investigating.

That’s when I remembered an old MSFS2020 thread about mainthread issues when leaving the sim’s audio set to “Default Sound Device” instead of explicitly selecting a dedicated device.

https://forums.flightsimulator.com/t/high-manipulators-thread-usage-when-audio-device-is-set-to-default/497252

And bingo that opened a can of worms. It seems that SU3 introduced serious sound-related issues, and that old MSFS2020 bug has made its way back into MSFS2024.

So I switched my in-sim sound from “Default” to a dedicated device. With that change, I was able to complete my first flight since SU3 where the mainthread latency didn’t** climb!**
BUT don’t stop reading here - it gets more complicated:

  • After every system or sim restart, the sound setting resets back to “Default Device.” (Sounds like another bug.) So you’ll need to manually reselect your dedicated device each time you launch the sim. At least for Steam users, this bug seems to be known and can also be found here in the forum.

  • Once I consistently set the sim to use my Realtek device, I could fly without any creeping mainthread latency. The flights were completely stutter free… up until touchdown. But as soon as the wheels hit the ground, I started seeing pulsing CPU spikes.

Digging further, I traced those spikes to GSX. Now, don’t blame GSX itself - because it’s still tied to the sound issue. Here’s what I had:

  • I had GSX voices playing through my monitor’s AMD HDMI sound, while the sim’s main audio went through my Realtek card to the speakers.

  • When I disabled all AMD/other sound drivers in Windows Device Manager and left only Realtek enabled, then set GSX to use the same dedicated Realtek device as the sim, the CPU spikes on landing completely disappeared.

Since then, I’ve managed several full flights: no creeping mainthread latency, no spikes, fully smooth all the way.

Hopefully this isn’t just a fix for my rig and can help at least a few others here as well.

22 Likes
MSFS24 SU3 - Micro-Freezes