The CPU does indeed have it’s work cut out whenever terrain or objects are concerned. It has the job of calculating all the vertex data and sending it all over to the GPU each frame. The CPU also has the job of constantly recalculating the collision mesh vertices for the ground we are flying over. This very much taxes the CPU.
Another big problem is that physics engines really don’t like it when we change the shape of collision objects. They hate it. It causes memory issues and performance issues galore. This has to happen in the game because it has to keep updating the collision mesh based on the ground around the aircraft which keeps changing as we fly over it.
So it’s a combination of the two. It’s both a CPU and GPU related issue. Either way, lowering the Render Scale is a quick and easy fix to reduce the load on both.
Edit: Maxing out the GPU is not a solution to someone who is already GPU limited. Not everyone is CPU limited in the game. I’m not. I’m GPU limited. But as we’ve both said, altering the Render Scale option helps mitigate these types of performance issues regardless of whether it’s a CPU and GPU bottleneck.
Right. And my goal it to ensure that people who don’t know how to identify this stuff on this forum, who are struggling with the stutters and load balancing have a simple, one-change-per-step method to not only see how they are limited, but also how to adjust for it, no matter what hardware they have. It is a one-size-fits-all process.
If you haven’t read through it yet, I linked it at the top of the thread. Feel free to check it out, and even try it for yourself.
Edit: in the thread I posted, I refer to my Kids’ computers (9 and approximately 12 year old systems, respectively), and how I run the sim on those without stutters. Both are already GPU bound, and my method worked for their systems as well.
I can pretty safely assume that NO ONE is running this sim on lower-spec hardware than what they have, so I feel like I have the range of hardware the sim can run on covered on both extremes.
As I’m trying my best to follow and understanding what you are explaining here are my findings for now.
First what I did was Vsync on and locked to 30fps.
I observed the fps counter and I was seeing what looks like a sawtooth graph. Causing stutters.
Therefor I turned Vsync off again.
Note: I already capped my fps within the amd driver at 60 fps.
Next what I did was the render scale. I bumped it up from 100 to 150.
This was giving me the following details.
This increase came with the cost of fps as expected of course.
I compared this setting with what I had originally with 60fps.
Both results gave me a smooth flying experience however the method you provided give me stutters when panning the camera. This is only when panning the camera. Flying is smooth.
I need to do that flight to test out that specific region and see what happens there with these new settings.
This was what I witnessed the other day in that stutter area I referred to.
Check what drivers you are using the last couple are not good but 496.76 is very smooth on my rig. I recommend at least for testing do not cap your fps as it can hide issues and personally I always test in difficult scenery (PG or airports) with volumetrics and clouds enabled as I would do when simming. Set all graphics ultra, LOD and renderscale back to a reasonable level and start adjusting these upwards stepwise in a quasi alternate fashion, don’t forget to pan occasionally to check that you haven’t gone too far with LOD (if your framerates allow you can counteract this with more RS). After getting where I want I usually pull back LOD one notch just to make sure.
I could do but I am quite happy with 50fps LOD 400 and panning as smooth as it gets.
And with a slightly better rig I could even manage this in 4k, I still might as I haven’t as yet OC’d my cpu … However €1200 was my limit (although stupid gpu prices mean I’m about €200 over).
Yeah, looks like you need to roll RS back a notch, then reduce LODs accordingly to keep MT from going red. Just keep alternating RS and LODs down until the stuttering is reduced to a point where you are happy. Looks like you won’t have to back it down much to get it where you want it based on those numbers, but how far you take it is up to you.
Tuning out stutters completely for panning is tough to do, and as I said in my tutorial, even I made a compromise for the occasional hitch. But mine appears to be CPU related.
Keep an eye on rdrthread if you get heavy stutters despite your MT and GPU latencies being set to spec. Something weird happened since the last WinOS update (I think…still investigating but I can’t reproduce conditions on demand yet). If rdrthread is spiking heavily from green to red/black in chunks on the graph, shut off the computer, then turn it back on. Not restart. Full power off cycle. Then try again.
Actually, with the FastStartup option ON in Windows, which is the default, Shut Down is more like hibernation while Restart is what you want if you want to clear everything.
Shutting down a Windows computer actually creates a deep hibernation file that the PC later leverages to allow for Fast Startup. A restart, on the other hand, completely kills all processes, clears the RAM, and clears the processor cache.
Thanks for this info, it has cleared up a puzzle that has bugged me for days (re. Imdisk advice to disable fast start when in earlier versions of windows it was required for persistent data)
I guess I take for granted that people know to disable fast startup immediately upon entering the BIOS for the first time, the same way you ensure XMP is enabled.
Regardless, shutting down the computer clears the rdrthread hitching for me.
Try to reduce the slider for global rendering quality, (the one thet cam be 400 at maximun) I have experienced that flying very low needs to lower that slider to 100 or even at 80 !! no great quality reduction but lot more fluid !!
Everyone’s hardware is different but yes they should definitely start off at a lower terrain LOD than they usually fly at. … Conversely it is best to start with graphics high, even ultra except renderscale which along with the LOD is used to adjust for smoothness before lowering graphics for more fps.
I lined up at a runway at La Guardia airport.
As you said pulling back the RS a notch I pulled it all te way back to 100.
Then I turned gpu related settings to Ultra. Had to restart after I was done.
Back at La Guardia I tweaked the RS slider to 130.
Lod sliders are set the way they were.
Now on the runway I’m getting 40 fps and in the air over manhatten 35fps. Experience was smooth even the camera panning wasn’t too bad. Must say I wasn’t disappointed that much.
I think I’m going in the right direction.
However!!! I did that testflight in the alps again after the test at La Guardia. You already guessed, yes, same spot, stutters again.
This confuses me. Why am I experiencing heavy frame drops in that particular area?
Have I missed something in attempt to tweak the settings accordingly to the approach you provided or could it still be the scenery as earlier expected by me?
If it is the latter, then I could revert my settings the way they were or is this the better option?
Sorry for my ignorance.
This picture was taken over manhatten with the “new settings” RS 130 and most settings to ultra.
Honestly, I have no explanation as to why you are having trouble in that specific spot. Those render latency bars look real good though.
What is your rdrthread doing when you get those stutters?
I have been scratching my head for 2 days now trying to chase down a render thread spiking problem that appeared all of a sudden, and I cannot track down the source. There is not a setting combination that can stop it. The only thing I have left to try is roll back the GPU update, and if that doesn’t work, roll back the last Win11 update.
A render thread spike I hear you say. Maybe I’ve seen some similar behavior at my end.
As I fly I’m seeing these brief temperature increase on the cpu, spiking it to a 70 degrees. This spike lasts just a small second and comes with just a short stutter.
This happens frequently throughout the entire flight.
That CPU behavior is the scenery loading I described in past posts, perhaps in a different thread.
Yeah, the rdrthread issue presents as some heavy stuttering in that render latency bar when looking straight ahead, but if you start panning, it straight up freezes, the rdrthread bar goes haywire.
If I remember correctly, you have an AMD card, so if you aren’t experiencing this specific rdrthread issue, then that leads me to believe that my Nvidia driver update has done me dirty.
