Intel i9 10900K - Limited by Main Thread [After WU7]


First of all, I’m not a tech guru so mostly I don’t understand why things work and why they don’t.
Before WU 7 I had a very stable system / settings with mostly mid 40-s anywhere in the Sim, now I’m at best low 30-s at FL350, Mid 20-s in a default airport out in the Swedish woods and very very low 20-s at international airports with a lot of stutters. (1440p)

Checking developer mode it says im limited by Main Thread (CPU usage 15%, GPU usage 60-70%) and no matter what settings I change it won’t make a difference.

When checking processes on task manager it shows that CPU 19 is at 100% all the time while the remaining “19” at <15%.

So far I’ve tried turning off virtualization in BIOS and selecting all cores in msconfig.exe > boot with no positive results.

All help and tips are very appreciated!

i9 10900k
RTX 3070
32GB RAM Venegance 2666

There are so many threads on this already. Mainthread limited is very common. Your GPU load to CPU load needs balancing. Reduce your CPU load and increase your GPU load and mainthread limit will reduce.
Terrain LOD/Object LOD reduction (say to 200/100) will help reduce CPU load.
Are you running 1440p or 4K? if at 1440p then your 3070 GPU is likely under utilised so needs more load to balance it. Otherwise you can see stutters.
If the other graphical settings are high/ultra already and GPU still under utilised, increase render scale to keep GPU busier. (125% or 150%)

Also consider locking sim at 30FPS for all round smoothness as per this video. Take note of all the settings he mentions.

I have a very smooth running sim by using these techniques.

Will check, thanks!

Thing is that I’ve already tried the “in-game” and Nvidia settings and everything was good until last update, regardless of low or ultra settings main thread shouldn’t limit that low in my opinion

Maybe you were not fully optimised previously, and WU7 has just somehow tipped? your system. I’ve not noticed any difference post WU7, there were no sim tweaks in the release, just scenery and scenery updates.
Maybe double check all your bios, drivers, NVidia drivers etc are up to date too. I’m using the latest game ready driver on Win 11 with no issues seen. (remeber to clear your directX shader cache after any NVidia driver upgrade/install though).

How do you check for bottlenecks?
I need to do that, just started pairing a RTX 3080 with a Ryzen 5 3600.

It is very smooth, but need to balance it as much as I can.

I have the same issue with the i9-10900F. At ultra settings with the sliders sat at 300, and LOD 150 - at 4K with AIG traffic turned on and in the A32NX at JFK (on the ground), I get around 24-27 FPS on the take off roll. It doesn’t look good. Is this the same for you guys??

I’m main-thread limited, but I do wonder if I’d be getting much better performance with the i9-10900K without overclocking?

MSFS don’t really likes either the CPU and GPU over clocked, my issues got magically solved after turning off the over clock and installing the latest GPU drivers.


i found turning all the traffic (boats, cars, airport ground traffic, etc) all off gave me about 15 more frames


I have a 10900K what LOD are you using?


What LOD is your max before performance starts to drop?

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Also have a 10900k + 3090 can’t really go over 200 terrain- and 150 objects seems to have some effect compared to 200. Everything else maxed. My current issue is trying to get good performance with AIG at max. Otherwise I’d say at KLAS without traffic I get 40ish FPS on the ground which is pretty good. With traffic maxed I get 25-32 and not super smooth. Always a WIP with NI and all the different settings. Wish they could come up with some sort of auto settings tuner with low LOD while on the ground and 400 once above FL200. I have no issue running 400 while just a few K ft off the ground.


I have Terrain LOD 200 Object LOD 100
I run a 4K display so TBH 200 doesn’t look that bad

I chose Object LOD 100 as I get stutter at high density addon airports when set to 200.

I do recall using Terrain LOD 300 when playing on 1080P TV.
Obviously with the increase in FPS at 1080P going from 60FPS down to 50FPS when changing view etc, wasn’t too distracting.

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Yeah absolutely a dynamic LOD slider which increases Terrain LOD with height and/or decreases object LOD - would certainly help to overcome main thread limitations.

IMO having terrain LOD 400 when at an airport is a waste of CPU resources


Have you tried locking at 30FPS with VSync ON. It is super smooth for me. MSFS was designed to run at 30FPS with a monitor refresh rate of 60Hz (also important) I think.
FPS is really the wrong metric everyone is chasing & repeatedly with the same outcome it would seem according to now many threads on here on the very subject, all relating to mainthread being limited. Balance GPU (output res, slider detail, render scale) & CPU (TLOD/OLOD) load out so your mainthread isn’t limited then switch over to 30FPS with VSync ON in game. You may be surprised at the results - fluidity the goal not maxing FPS.


Terrain LOD at 200% is absolutely the sweet spot if you’ve got a decent PC. It doesn’t look massively better above 200% and FPS absolutely tanks. Even terrain LOD at 100% is perfectly useable. Its what we all made good with before the multi core optimisation last summer.

The terrain LOD at 300 - 400% is really just a future proof feature for the next generation of CPU’s and GPU’s.


I’m using 150 LOD and 300 Terrain Level of Detail


I disagree as in 4K you can see unloaded / melted looking buildings in the distance at even 300.

I think current hardware should be able to run it with some decent optimisations by Asobo. A lot of us on higher end PCs are CPU bound currently, but DX12 is not yet working properly. Once they implement proper DX12 and utilise multiple cores efficiently (rather than 1 single core) we could see some pretty good improvements in FPS.

Also, a lot of people are currently blaming photogrammetry for poor FPS on the ground, so Asobo could also work on this.

I’ve actually found out VSYNC gives me no improvemt

Your 9900K has 16 threads and the game pretty much only uses one of them, the other 15 just tick over at idle doing almost nothing. It is pretty normal on a 9900K to see the main thread maxed out and the rest doing nothing with an average CPU usage overall of maybe 15% or 20% .


Interesting, I’d say our performance is basically the same then. They need more CPU optimisations.