This has always bothered me and there does not seem to be any help for the DEV FPS window. I have been fooling with my computer performance and noticed that the main window here remains RED when all the rest are GREEN. My goal is to get 60 FPS as my monitor is limited to 60 Hz, and I seem to be there.
Can anyone help?
I do not like to see RED… irritating!
It looks like you are getting 30fps with x2 frame gen. I think 30fps is the lower limit for acceptable performance. That would explain the color.
Oh, so if it were running at 31 would turn green or if I turned off FG X 2 and let it run at 60 would turn green. I think it will run at 60 with the fast card and fast processor. 31 will not fit too well with the display.
I was under the influence of the new DLSS and NVIDIA driver.
Will try the experiment.
Thanks very much.
Experiment successful:
I was going to mark this as the solution but it raised another question that might be answered by you? Note the little yellow bar at the top green area and also below by by TLOD Factor. Any idea what this is… Dynamic Settings adjustment???
Sorry, that’s beyond me. Perhaps the developers will respond.
Thank you for asking the questions rookies like me want to ask.
The color of the FPS portion is red/green based on your display’s refresh rate. Seems like any frame rate at or above about 50% of the refresh rate turns it green. Also Vsync effectively reduces what the sim interprets as your refresh rate, so that changes when it flips from red to green.
Yes indeed. I am not a rookie but these are questions few can answer as there is no manual just guesswork, but some have been around a while and can make good guesses!
Just to add, as I need schooling myself. Why does the rolling cache read speed show spikes. How would you ck that part. Mine does that. 
This makes sense since my refresh rate is 60 and above 30 or so it turns green. Fits with what the first respondent suggested.
But, I am now mesmerized by those yellow blocks and their meaning. I feel like I am in an Egyptian Tomb deciphering hieroglyphics.
Those are indeed related to Dynamic Settings and represent a factor of your LOD setting. 1.00 = 100% of your LODs as set in settings. As your base frame rate dips near or below your assigned target for Dynamic Settings those values will drop as low as 0.50, which would be 50% of your LODs as set in settings.
So if your TLOD is 200 and the sim drops to a factor of 0.50 to try and hit your assigned Dynamic Settings FPS target, you will effectively have a TLOD of 100 during that time until the frame rate increases enough for it to increase the TLOD factor back to 1.00 (or anywhere between).
Thank you very much for explaining that!
Another hieroglyphic that needs explanation.
Again I have been hypnotized by looking at what happens rolling cache and read speed. You would think that they would be relatively constant and fast since I have a Gbit fiber system and a M.2 SSD drive. My hypothesis is that they have a funny interaction depending upon how much is available in the rolling cache and how much must be downloaded. It is weird because I fly a standard flight every AM pretty much to look at the local weather and it still downloads materials. You think that it would be fully cached by months of doing the same route.
Thanks so much. Seems so simple once you have the actual understanding rather than guessing.
I am going to look at the entries and make sure I have a reasonable understanding of every entry. It is a shame we have to do this when the development team could probably just give us a dictionary in a few minutes.
One more nuance. This AM I noticed yellow on time next to the ms number before the FPS but no other yellow. Maybe there is some hidden criterion for this one too. No other yellow on screen.
The frame rate is limited to 60. I guess I could try 70 or 80 and see if it goes away assuming the ms reading goes below 16.67. The main thread is in the 12 range.
If you’re capped at 60 FPS, you’ll always see 16.67 ms because that’s exactly the frame time for 60 FPS.
Try setting the cap to 70 or 80 FPS - or just remove the limit entirely. Once the FPS goes above 60, the frame time should drop below 16.67 ms, and instead of yellow you should see it turn green.
Yup, that seemed to do it. Cannot get the same frame rates as you but explains. The colors. I also had VSYNC turned on that synched it to my slow monitor.
I decided to make a list of for me the most problematic items in the DEV FPS window and maybe people can comment and this gets more accurate with sucessive approximations of reality.
MainThread = Best explanation I found was in forum: “Limited by main thread” only means the game thread latency is higher than the latency your GPU can achieve. This means your GPU is able to achieve higher FPS but the game is not finishing the main thread loop in time to achieve the same equivalent latency. Simplifying your example, what you have is the following:
Resulting render runs at 17.95 ms → 55.71 fps, which is equivalent to ((1 / 17.95) * 1000)
Main thread can run at 16.6 ms → it could only achieve 60.24 fps
GPU can run at 8.8 ms → it could even achieve 113.36 fps
RdrThread = Render Thread … Limited by RdrThread" in Microsoft Flight Simulator (2020/2024) indicates a CPU bottleneck where the Render Thread cannot send draw commands to the GPU fast enough, causing low FPS. It is often triggered by heavy scenery, VR, or, as users suggest on Microsoft Flight Simulator Forums, software bugs. Common fixes include lowering terrain/object detail, reducing resolution, or switching to Fullscreen mode.
Manipulators = Best Answer is complicated:
CoherentCTUIThread = The Coherent GT/TUI thread in Microsoft Flight Simulator (MSFS) is a critical component responsible for rendering the UI, including menus, gauges, and the glass cockpit (EFIS). High usage on this thread often causes stutters and performance drops when it becomes overwhelmed by complex 3D cockpit displays or UI elements.
Graphics Queue = there seems to be high/low and median values noted. I found a reasonable AI explanation of some of the details of this metric:
The “Graphics Queue” Breakdown
When the FPS display shows “Limited by Graphics Queue,” it means your GPU’s utilization is at or near 100%. The CPU is currently waiting for the GPU to finish drawing the last frame before it can hand off the next one.
| Metric | Meaning | Solution |
|---|---|---|
| GPU Time | The actual time it takes the GPU to render the frame. | Lower resolution or GPU-heavy settings. |
| Graphics Queue | The buffer of commands waiting for GPU execution. | Reduce “Render Scaling” or use DLSS/FSR. |
Specific Settings that Stress the Graphics Queue
If you see a high MS (milliseconds) count in the purple/red Graphics Queue bar, these specific MSFS settings are the most likely culprits:
Render Scaling: This is the #1 factor. Setting this above 100 puts massive stress on the Graphics Queue.
Anti-Aliasing: Using TAA is demanding; switching to DLSS (Super Resolution) can significantly clear the queue.
Volumetric Clouds: One of the most GPU-intensive settings in the game. Dropping this from “Ultra” to “High” can save 5–10ms of GPU time.
Ambient Occlusion & Ray Tracing: These are purely mathematical GPU tasks.
Texture Resolution: While mostly limited by VRAM capacity, very high resolutions require more GPU “cycles” to map onto 3D objects.
AsynchComuteQueue = Async Compute Queue is a DirectX 12 feature that enables the GPU to process non-graphical tasks—like physics, compute shaders, or shadow rendering—simultaneously with main graphics rendering. This parallel processing improves GPU utilization, reduces latency, and increases FPS by preventing idle GPU resources, particularly on modern hardware.
FiberBdgt = This looks complex and best I can do is some AI: In the context of MSFS, FiberBdgt (Fiber Budget) typically refers to a performance setting used to manage how the simulator allocates CPU resources for rendering scenery (off-screen or background tasks) versus maintaining a stable frame rate.
FiberTime = Actual time of reads (ping?). AI note helpful here.
Windows defender was causing my issue along with a network setting. All good now with those red spikes on overlay…
One more hidden service that sneaks in is OneDrive. I use my computer for other purposes and at time OneDrive will be active… if any risk good to pause. I close the browsers for sure as who knows what is going on there under the covers. Mozilla it seems for me is worse than Chrome.
