Big Fps drop SU6 LOD200-400 CPU Hit

Well speak for yourself :stuck_out_tongue: My OC’ed 16 core 10700K / RTX3070 combo was running at 20-30% CPU usage with 50-60fps before SU6 (Ultra settings with WQHD, depending on the location and other factors ofc) and now is at slightly increased 25-35% CPU usage but fps decreased to 25-35 fps (in the same locations with same settings (LOD 200/Ultra)…
I understand what you want to say and i also agree with you on most parts, but at my system the CPU is far from being at its limits. Moreover it’s actually bored out most of the time. Seems like their “optimizations” have nothing to do with using the cpu ressources more efficiently, but just adding/removing different performance eating features in order to suffice the community requests… thats far from improving the code in my opinion.


I expect you are correct. The optimizations in this case are not optimizations but “enhancements”. An optimization would infer a performance improvement with no discernable difference in quality. An enhancement would be a noticeable improvement in visual quality at the expense of performance. To maintain the same level of performance a user would have to reduce the enhancement back to pre update quality.

What you are describing is a 50% drop in performance. I am not sure the enhancements would warrant that. I noticed a minor increase in load for the enhanced visuals. I would have to guess something else is going on. What is your current GPU load and memory allocation?

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My GPU load is at 100% most of the times, since they improved the streaming in SU4, from my 64Gb Ram also approx. 20-22Gb are allocated at max. I deleted the rolling cache and rebuilt it with 32Gb (using a ramdisk for this now, to reduce the write load on my nvme ssd).
Drivers etc. are also all up to date, I’m still on win 10, maybe the boost only comes with w11? :laughing:

I am running Win 10.
What resolution are you running?

As mentioned WQHD (2560x1440)

That’s not exactly true. Increasing the LOD to 400, 600, and 900 significantly increases the VRAM usage when I did some comparison tests on my rig with a 3090 and 5950x during the pervious world update. At first glance, there is an increased CPU overhead, but most of these assets from higher LOD settings get offloaded to VRAM if available. Once your VRAM gets maxed out, it gets offloaded on the slower system memory. This is when performance usually decreases significantly.

In short, I would not increase LOD beyond 200 if already maxed out on VRAM usage, especially at 4k resolution. VRAM bottlenecks will destroy performance in this case.

It has been mentioned a few times that CPU/Mem are the most affected. I indicated that the load on the CPU is increased not the load on the GPU. Not sure how an increased load on the Vram as well negates that fact. The primary complaint is that users are becoming limited by the main thread. That would be the CPU.

The bottleneck is on the CPU, not the GPU. Vram over usage does not mean the GPU is over loaded.

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Hi fellow simmers!

Here are my impression with same 4k ultra settings and aircraft at same airport (except contact shadow set to high, refresh rate low, windshield effect high - exact same config as SU5 + hotfix).

  1. Final approach and at airport at ground level: Increase in ±3 FPS (46 fps at SBSP).
  2. 1500 to 2000ft less 3, 4 FPS (41, 42 fps at Sao Paulo).
  3. During daytime lighting and shading seems noticeably improved (less bright, more contrast and more like pre su5)
  4. Reduced stutter (had few during taxi turns after latest SU5+hotfix)
  5. More detail in buildings and at 200 LOD seems slightly increased draw distance (maybe this explains some minor fps impact);
  6. Night lighting is much, much improved: better LOD of street and road lights and the lights are also much more “defined” (using 4k tv runway lights seemed big and blurry for example after SU5. Now they are sharp!)
  7. Frametimes are better. SOOOOOO much smoother.

Fine update for me. Totally manageable tradeoffs, if any. Congrats MAsobo! Congrats indeed! Must give credit where it is due.

hope this is not caused by the lack of AI and multiplayer traffic at this moment!

intel 10900k, rtx 3090, Z490MB, Firecuda Nvme 2TB, 32gb @3700mhz


Main thread bottlenecks are just a limitation of DX11 rendering pipeline, not necessarily increased LOD. The fact that I can push LOD to 9 with minimal impact on my rig (although with a 5950x) suggests the CPU is not the exactly the only bottleneck at high LODs.

I would be willing to guess most users that are getting very poor performance at LOD set to 400 are maxed out on VRAM.

Sounds like we have very similar systems. I also have an OC’d 10700k, 32GB Ram and a 3080 running 1440p and have also noticed some performance issues. Just doesn’t seem as smooth as before, especially on landing. I seem to lose some frames during cruise, and then a bit more on landing.

Monitoring my fps it says I am constantly limited by main thread and Core 15 is always at 100% even if I put the settings to low….the only thing I have found that helps the mainthread is turning on vsync in the msfs settings,

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SU5 vs SU6, graphic wise, it was more blurry at far and less defined, shorter draw, less trees, night light worst with SP filter on all altitude etc…
MSFS Sim Update 6 - Comparing the much improved terrain detail at the new level of 400 - YouTube

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I see, thanks for the input! Do you use the Ingame Performance Monitor of the Dev mode or some external tool? I check it with task manager and MSI Afterburner OSD. I have no bigger peaks with any of the 16 cores, there are two that are more active, lets say at about 50-60% at max, while the other 14 are idling at 5-10%… but none of them is near 100% at all.
I have an g-sync compatible monitor, so i have v-sync disabled and benefit from variable refreshrates. Not sure if i want to activate it, but for testing i might give it a shot.

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I monitor with both Afterburner and Dev mode and task manager, they all give quite similar outputs. I have g-sync as well and have it enabled


Well, today I took 2 flights, both around 250 NM. I have started with 30 fps at gate, but on ground of destination airport I had only about 25 FPS. So I tried to reload flight - started at the destination airport, same weather settings. Magically I had again standard 30-31 FPS.

Does your FPS also decrease during flight?


Instead, limit your max FPS in nVidia Control Panel. Experiment until you find a value where you’re no longer limited by main thread.

Mabye you overlooked my statements from before, but i am by no means limited by any main thread. When MS2020 is running, 1-2 of my cores are at maximum of 50-60%, but only when im over big cities, so there is no CPU bottleneck.

Sorry, I assumed too much from your dialog with the Colonel. :roll_eyes:

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No problem :smiley:

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LOD more than 200 reduce my GPU usage and increase my CPU usage.
On screenshots, left top corner my GPU and CPU usage with lod 200 and 400 during a flight

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Yeah. LOD affects CPU render latency. It has almost nothing to do with the GPU. You increase LOD, your CPU render latency increases. FPS drops. These are facts.

All the speculation and misinformation people are throwing around this forum is ridiculous.

The developers have stated over and over again that they optimized this sim for 30 fps at 4k on current hardware.

There is not a CPU available that can run this sim at 60fps under all conditions.

It is not that difficult to tune your settings in this game for a smooth, high detailed experience.

Trying to base your settings and performance output on percentage of utilization in task manager doesn’t work. Render latency is the only metric you should be using to set your sliders.

Open the dev mode window, turn on your fps counter, and pay attention to your main thread and GPU latencies.

Set vsync to 30, increase GPU-bound settings (basically every slider EXCEPT LOD) so that your render latency is as high as possible, but stays below 32ms under your highest-load situations (I use Central Park, NY for tuning). You may have to increase your render scaling if all of your GPU bound settings are maxed out.

Once your GPU settings are set, reduce your LOD sliders until the main thread stays below 32 ms under your highest load situations. If you start seeing “main thread limited”, and your GPU render latency is at or slightly below 32, you need to reduce LOD some more.

Once these settings are made, you can turn off vsync again to chase whatever magical FPS number helps you sleep at night, but you will start seeing microstutters again, because once again, your CPU will be struggling to keep up.

In my case, I have to run my 3060ti at 4k through DSR, reduce in-game render scaling to 75%, and run all other sliders and settings maxed out (again EXCEPT LOD BECAUSE THAT IS NOT A GPU FUNCTION) to ensure that I don’t get into mainthread limited conditions. I also had to REDUCE LOD from 200 each to 190 each to adjust for the developer changes in SU6, and thats on a 10700k at 5.1 all-core. My vsync in-game says on at 30fps.

It’s not rocket science, and having the biggest, baddest GPU on the market will not increase your FPS in MSFS. Period.