Your main thread limits you most on the ground, where far more CPU calculations take place. The sim is managing more traffic, ground physics AND air physics at this time, while also calculating all the airport life, ground and plant texture geometry and data, and photogrammetry. Once in the air, things become simpler for the CPU, as it doesn’t have to compute all that traffic, ground handling, plant, and airport life.
Even if a CPU is multithreading perfectly and efficiently, each core will have to wait for another to finish its calculations to combine them to help tell the GPU what to draw, so it always takes more time to make a frame than it takes the CPU or GPU to cycle a frame. This is compounded further by sometimes having to wait for things like RAM, VRAM, and bandwidth streams.
The TLDR is your CPU is only as fast as its most overworked core. That core will take the longest to complete a frame cycle and all the other parts of your computer will need to wait for it to finish its cycle before they can all combine their calculations to produce your next frame. And it is all but impossible to spread all that work evenly between cores, you can only make it more efficient, and 2024 is more efficiently multithreaded than 2024, it just still has a CPU bottleneck you must often work around.
It appears that you are using big, detailed tubeliners at large, complex airports. From the photo you posted of the cockpit, the fps window at the bottom shows around 11GB of vram being used out of 10GB available on your 4070TI (from what I can see on my little phone screen). So what this means is that the data over the 10GB vram limit of your gpu is being cached in system memory which is slower. Your cpu will then have to wait on the slower memory access and this can cause stuttering. Gpu vram is typically very fast GDDR6 ram that is much faster than your system memory.
You can monitor the vram usage as you fly and see if any stuttering occurs immediately after vram useage goes over 10GB. If it does, then you need to reduce the screen resolution or turn down the detail oriented sim parameters like tlod, olod, texture resolution etc so that vram usage stays under 10GB. Another option is to buy another gpu with more vram .
So try this out and perhaps this will help resolve your stuttering issues.
Maxed out VRAM will always be a serious bottleneck, but I get low GPU,CPU usage, very low VRAM usage and very low bandwidth usage, so something else is causing the problem.
Made some replacements and tests - it is almost okay and I can fly.
But still freezes and lugs right after landing.
FPS is going to be 15-20 and norhing can change it.
Don’t know what else to fix.
It’s happing after every landing.
Screenshots in PARO (Buthan) with no traffic both on ground and in the skies. Perfomance is very low. After I go to menu and wait for about minute is goes okay to 70-80 fps back.
What is wrong?
As I mentioned in my previous post, if you turn down the parameters which involve the details which fill up your vram, you can avoid at least some of the stuttering. When I do this with my 2nd PC which has a gpu with 12GB of vram, it runs much better.
I saw this as well. That’s a guarantee that FPS will drop (sometimes drastically.) Until they fix the DX12 memory allocation issues you need to do whatever it takes to reduce VRAM usage.
I can’t really help guide you, because my GPU has 24GB VRAM, and I’m not having the same problem. I did find this helpful guide to which settings affect the CPU and the GPU.
Has anyone tried putting there resolution lower in there pc display settings and then upscaled to there monitors native resolution in the sim? Im not very good with tech but everyone seems to say downscale in the sim for better performance but that dont make sense, upscaling in the sim seems to make more sense in terms of what your asking of your cpu and the upscaling is done by the gpu.
I have a similar issue, but I have no saturated cores. My most heavily loaded core is often at 60-70%. Dev mode will list me as limited by main thread, even with my GPU pegged at 99-100%, and CPU load to spare.
I think it’s the definition of “limited by mainthread” that is the ussie here, as I am clearly GPU limited, and the sim telling me i’m limited by mainthread, with single core headroom to spare.
I have spare VRam and main RAM as well, and no other bottlenecks that I can see.
Look at the times on the cpu line and the gpu line in the fps window. This is how much time each is spending to produce one frame to be sent to your monitor. There you will see why it’s saying you are limited by the mainthread.
Not an expert but I believe chip like the one I have, Ryzen 7950 with 16 cores have basically one best core and a second best. I believe they have been optimized to run the best with the temperature constraints of your particular chip. In other words, these are the fastest cores and are the rate limiting step of a serial processing system like this flight simulator.
Some secondary functions might work on multi-cores but you still have to sequentially create an animation one frame at a time. I got the Ryzen for AI/astrophotography and I use the CUDA Cores of my 3070ti for that… my problem is of course the 3070 is VRAM limited… would have gotten a better card had I though my system was to be used for MSFS 2024.
I just swapped my GPU for a faster one. I have been GPU limited pretty hard with the RTX3090, and that’s fine. Smooth gameplay, with just very occasional stutters and slowdowns when loading new scenery and such.
With the faster GPU, I get 60-80fps for a few minutes, but the second the CPU is saturated, the sim grinds to a halt for 1-2 minutes. I get 15-20fps when that happens.
Now, that’s understandable, to an extent, but I think there should be a way to improve the timing of the main thread so that it can stay near saturation, and slow down the sim appropriately, instead of just collapsing. I play many sims, but this is the only one that just fold when the CPU is overloaded. Most just reach a plateau of performance and stay there.
And while the “solution” is to throw more work on the GPU to slow down demand on the CPU is not REALLY a solution, it’s a bandaid at best.
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