CPU Bug "Limited by Main Thread" is causing the bad FPS

see how your CPU usage differs from mine?

then obviously something is different on your end than my end. notice how all my cores and threads are balanced?

falls right back to, you have something set differently than i do. explore all your settings and tune them till you get the best results just like i spent the 6 days worth doing so.

here is another example of all 3 of my screens, notice the near perfect balance of my CPU?

And another one showing pegged CPU during scenery loading in.

and a third, after the scenery loading, showing equal tasking.

sorry, but you are going to have to find out why your CPU is tasking its single thread issues that way. ive figured out mine

sorry wrong initial image

no, i will not post a alpha link, to this section of the forums, I AM NOT ALLOWED TO DO SO.

Yeah, I can see that your CPU usage differs (edit - actually, in 2 of the 3 situations you’ve posted you also seem to be CPU bottlenecked).

I can also see how the playing situation differs. From the screenshots you posted, you seem to be GPU bound - GPU utilisation up between 96% and 106% (???). If you were to try that same flight again with the developer tools on, I guess you’d see “Limited by GPU” not “Limited by Main Thread”. This is also the case for me when I’m up in the air like that. My FPS is around 70 and it says “Limited by GPU” - perfectly undestandable.

What we’re all talking about is when this changes to “Limited by Main Thread”. This screenshot was taken simply on the ground in Barcelona El Prat in a Cirrus SR22 sat at the end of the runway. Since this airport is very close to the center and has photogrammetry for La Segrada Familia, it’s using lots of CPU resource for doing that. This means that I’m being limited by my CPU load. As you can see, this is causing my CPU to be used 100% on one core, meaning I’m limited by single core performance.

You’ve previously said I’m catagorically wrong on that but the proof is in that image and your own response to it.

Now, since this doesn’t seem to be getting us anywhere, I don’t think there’s much more to discuss. I posted by conclusions (in post 331) and I stand by them. Without the developers improving the game engine and/or implementing DX12 support, then most of us will continue to be CPU limited most of the time unless we go about overclocking the CPU. I also stand by that adding more CPU cores will not make it better if they are running at the same number of calculations per cycle and the clock speeds are the same. This is because it’s the single core performance of the CPU which is holding us back, not overall CPU usage.

Finally, I heavily doubt that posting a link (which presumably is protected by a login etc) violates your NDA.


read that and then stop barking at me about the rules of Alpha testers posting links and information contained in the alpha.

the only two things you have not told me, is what power plan are you running ( and having attempted to unhide the “Ultimate Perf” power plan, ) and if you have checked your CPU Park status and tasking limits.

and if you cant figure out how im getting 106% GPU Usage, google it.

other than that, im done talking to you. figure out your CPU with others.

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Nowhere does it say that you’re not allowed to post a hyperlink which you’d need to log into. This is not sharing pictures, videos or information from previous test builds, nor is it comparing test builds to release.

An alpha tester should be able to follow the link to somewhere they’re allowed to have access to while others like me will not. No issue there.

As for the other 2 things - yes I’m running in ultimate performance power plan.

When it comes to CPU parking, I don’t know much about it. This is perhaps where you can become really helpful to a large number of us on this thread since it may well help our problem. Are you able to explain what it is and how we’re able to use this to help us?

And I’m not barking mate. I’ve tried to be really measured in my responses. I’d appreciate the same.


post links to the closed alpha section or revealing the —> INFORMATION <— contained within that section to the PUBLIC RELEASE section is NOT ALLOWED.

says it right there in the post:


send a message to the Community staff if you dont believe me. im sick of arguing that with you, you are borderline asking for me to block you because you seem to know the rules better than anyone else yet, you havent even been part of these forums for more than 3 weeks.

now, CPU Parking and Tasking Limits -

get this little app

watch your CPU during sim activity and see if any of your cores/threads go grey, if they do, disable CPU Parking outright.

come back then tweak your settings in the NV CPL for DSR, AA/AF Settings, Threaded Optimization, the entire list of settings, it takes time to figure out the best settings. your settings will differ from mine.

say one more thing about posting links or information from the Alpha section of the forums and you will find all this information gone.

@anon33898240 is correct. The NDA Reminder posted by Microsoft makes this clear. This forum is for the discussion of the release version of MSFS only. Thank you.

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There’s no need you be so aggressive. We disagree about the rules, sure. We seem to have a different interpretation. But there’s no need to be so aggressive.

And as for “all this information”, you’ve given a link to an app - ParkControl.

As far as I’m aware, you’re not a moderator and aren’t able to simply block me from the forums because you have a personal grievance with me.

I’ll take a look at the app but don’t be so aggressive. There’s no need. Everything flows better if you simply keep things chill and provide reasoned arguments, backed up with evidence.


Thanks for the clarification @Sartanius.

It’s unfortunate to see that even links to closed sections of the forums which only alpha testers would have access to is seen as information.

None-the-less, thanks for clearing that up.


actually, i can block you. personally on my end, personal blocks that prevent you from interacting with me or even seeing any of my posts, if i so desire.

no need for a mod to do that. it’s called personal block list, just like facebook and social media does.

and you are itching my fingers to click it.

Once again, really aggressive. I simply don’t understand why.

Let’s all come together collaboratively, to help each other rather than being this aggressive eh?


It is unfortunate that users of sim do not have the knowledge to balance the game, as stated.

I still think it’s a bit of an ask for regular users to be tweaking the settings to this great degree.

I understand that this is an opportunity to learn, but spending 6 days to tune my system to get a good experience is a bit too much.

I would rather have Asobo Microsoft explain this officially, so I can either get some profile to support the reasonable level of performance or detailed guidance on tweaking.

Seems a bit outrageous that we are left to our own devices.

I appreciate it’s a new game, but I would assume alpha beta testing is there to find all the issues and align the performance against suggested hardware published by Microsoft.

Anyways, I better get cracking reading them settings lol.


I wonder, if his agressiveness is only here on the forum. If thats true in real life also… Dear lord. Hhahahahaha


sadly, thats how it is for a lot of major software titles that take on an entirely new type of software design.

This is Asobo’s first ever full fidelity sim, and the level of complexity.

@ClammiestPick15 thank you for that …


Thanks for what?

it took that long because of the major changes with updates we got. it was about 6 days total time, from first getting into the sim program till public release.

Could your discussion not better be handled via PM?

I mean I am for open discussion, but I do not see what would be the benefit for the general public (imo).

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portions of it are in PM

Imo the moderation team here is extremely lenient when it comes to locking threads. Which I highly commend as we have many important things to discuss.

In most other forums such a lengthy battle between 2 users would have been locked, because it is a personal matter.

Better just agree to disagree and let it slip. Probably both of you have points that various people agree with.

CPU limitation is not new to flight simmers (because of the need to process huge amounts of geodata), so there can be no clear winner here. You need a fast CPU and RAM and generally a lot of bandwidth, while the GPU is there to render high resolutions and high quality shaders.

Just my 2c


Please discuss topics, not people.

And please be respectful to each-other.

Really, it’s not that hard.


I have run and rerun the virtual cores on and off… I get much better results with them on. CPU not maxed out, all cores about even. 20+ gain in FPS.

I7 6700K @ 4.5