Sim Performance Terrible when Limited by Coherent GTDraw

I’ve been flying MSFS 2020 off and on the weekend. I have a decently robust system (11th Gen i7, RTX 3080). I normally get good performance and hear the fan when the machine is pushed. I normally get a very smooth and playable 40 fps on the settings and resolution I use.

However, sometimes the performance in MSFS 2020 is terrible. By terrible I mean a choppy stuttering unplayable 8-10fps. It’s random. Sometimes it’s hours into a long flight - other times, it’s when first starting up. Sometimes it doesn’t happen. It makes no sense. When this is happening, the machine is not thermally throttling - the fans are hardly running -something is causing the sim to limit, such that it’s not utilizing my machine to its capacity.

Nothing is wrong with the computer. I troubleshoot - other games play fine. PC/GPU benchmark tests work fine. PC fans running fast and machine performs well.

So, in developer mode, whenever the machine performs well in the smooth 40fps, the machine is typically “Limited by main thread”.

When the performance is abysmal and unplayable, it is always states “Limited by Coherent GTDraw PC D3D11”. I have no idea what that means, what is causing it, and if there is anything I can do to troubleshoot, or if that is an MSFS2020 sim bug.

The millisecond timing on the “Limited by Coherent GTDraw PC D3D11” is 4x the next lowest, which is the GPU, but the GPU is barely being utilized when the sim is limited by this, and the GPU fan is running low (GPU temps not hot either - no thermal throttling).

Is this is a sim bug, or is there something I can do to fix this?

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Here’s an explanation of that function from another forum member. It’s not you, it’s the sim, and maybe one day it will be fixed.

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Thanks. Figured it was the sim, as troubleshooting found nothing wrong with the machine and other games played fine. Sadly, my other games played fine with my old machine - I spent close to $3000 on a machine solely to enjoy this sim (it is fantastic when it works). Hope MS/Asobo is aware of the issue and actively working to address it.

The most bizarre thing in my opinion is that some people have literally never had this happen, including me. And my system is not as powerful as yours either. When they fix it, I would love to read the technical root cause analysis.

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Most probably a driver conflict of some description and not necessarily graphics … or old, incompatible software, some simmers are very stuck in their ways.

If it were anything like that, any one or even two variables, I think the resourcefulness of the people on this forum would have found the magic recipe by now, especially after 1600 posts in that never ending thread.

Despite some more isolated reports of this bug being attributed to a page file setting or rolling cache issue, I firmly believe the true cause of most of these reports is embedded in the sim, with users basically helpless to fix it on their own when it happens.

The most promising lead is the third party developer that was able to get MS/Asobo some recent debug info to lead them to a real memory leak. When patched, maybe that will be the magic bullet. Or, maybe it will fix some reports, with something else still lurking deep in the code continuing to cause issues over time.

It might be already fixed by Asobo.
Data & video was submitted to Asobo, and they report they found & eliminated a memory leak,
This was quite recent, so it may or may not get into the next SU update

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