The performance of my PC is limited by my CPU, so I have done quite a bit of research of the causes and solutions, and have come up with this overview table which I hope may be helpful for other people with a limited understanding about this. What do you think about it? Did I get anything wrong or did I miss something important?
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One recommendation that I have is to change your definition of CPU-limited/CPU utilization to main thread limited as per the FPS counter in the sim. While the main-thread (1 thread on my 5900x) running the sim can be maxed out at 100% causing stutters the other 23 threads are not close to maxing out and my CPU utilization only shows 25-35%.
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Thanks for your feedback @WingWarper1 What can be done when the main-thread is maxed out? Is the Process Lasso tool a solution?
I would add “High LOD settings in MSFS, specifically TLOD” to your performance limited by CPU list of causes as I come across this often helping people out with MSFS performance issues caused by limited by mainthread.
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What can be done when main-thread limited has generated much debate in many threads on this forum along with YouTube videos. The challenge is that everyones system is different as far as CPU and GPU capabilities and one solution does not fit all.
I’m not familiar with Process Lasso but on quick study of their home page I would say that tool is probably best utilized by a highly skilled computer scientist.
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I would add that in my case I have tried to get the GPU to run at 100% (or nearly so) all the time, that’s what it’s designed to do and it doesn’t cause stutters or other problems…stutters are caused generally when the CPU is at 100% on one core/thread and the GPU has to wait. I am a VR user and have always used 100% of my GPU (both a 3090 and now 4090), and tuned the graphics settings and OS settings such that the CPU is not maxed out on any core and this has given very smooth performance and good FPS. Also, I would mention that when folks try to run ultra settings it consumes a lot of CPU in particular and the visual difference is not that noticeable but it can introduce stutters even on high end equipment, so even with a 13900k and 4090 I don’t run ultra settings, I run high and it’s a meaningful difference in smoothness (measured by 1% and 0.1% fps lows) and overall fps.
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Process Lasso (I use it) is indeed a powerful tool but it can also cause a lot of instability, crashes and other problems if you try to control certain programs and override the windows process scheduler. As an example, if you use it to try and force MSFS to only run on certain cores in my experience the sim won’t even launch at all. I use Lasso to force background tasks to the e-cores of my 13900k and that frees up the p-cores for MSFS and does improve my results overall…but I carefully did this for just a few programs and tested each time to make sure it was all stable and no CTDs. I would say Lasso is not a general tool for most folks unless you want to tinker and wade through the many pages of documentation that comes with it to really know what it’s doing. It has also helped me in VR as the VR software was stuttering when using p and e cores and forcing it to p cores only helped solve that (although the Varjo company will address this in a software update soon so the use of Lasso for this thing won’t be needed any more)
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Thank you @WingWarper1 ! Would you be so kind to give us sort of a rundown of this debate? In your experience, what has worked to solve a mainthread limitation? Does this differ from the advise I give in my table above about CPU limitation?
Thanks @tempestornado23 ! I am curious: have you noticed a big improvement in your VR experience when you changed from the 3090 to the 4090? Because I am also considering getting a 4080 or even a 4090, along with a much better CPU, but that costs a lot of money and I am a bit afraid it may result only in let’s say 10 FPS more and a little bit less of stutters.
Yes, the move to the 4090 was a very meaningful jump in both FPS, smoothness (0.1% and 1% lows that cause stutters), and the ability to increase graphics settings – as long as you have a strong CPU as well. I am happy I did it but I already had a 13900k cpu and was able to sell my 3090 to partially offset the $2k for the 4090. I think the 4090 is the largest improvement for VR that I have made so far.
I would not recommend a 4080…save up more and do the 4090 if you looking for the best VR uptick from a 3x series card.
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Just to clear up one misconception, GPU’s are designed to run at 100%, but CPU’s are at peak performance at 50% utilization and are struggling after 85%. You want to keep your GPU load as close to, but not over 100%. A tool like GPU-Z is good for monitoring GPU load.
Just do a search within this forum for “mainthread” and you will get thousands of hits (the search engine eventually asks you to narrow your search there are so many hits). Imho it is not something you can resolve within a 1 or 2 (or 200) page document.