I would guess it is the ISP or FS servers throttling your usage.
I have had the same issue before. It seemed to be being caused by the coherent gt draw, which became the limiting factor and slowly got worse over time.
Same as you, hitting escape and then going back into the game fixed the problem for another 20min or so (gpu back to 100% utilisation and being the limiting factor). Possibly a memory leak of some sort?
Min 7:36 https://www.youtube-nocookie.com/embed/vA8hChmErio its partially fixed what ever it means.
Hopefully it means that they still fix it to bring it in the next update and it will remove all these stutters and poor fps over which you can read also here: Still Stutters and poor FPS after the 1.14.6.0 Update! - #169
Not sure of the title can be changed. And anyway, there are still lingering problems since 1.14.5.0.
Asobo has said that some issues were resolved, but performance problems from that upgrade still exist and I guess Asobo is still working on fixes brought in by that upgrade.
Hi, thanks, can you explain this in a little more detail? I watch this in detail. Usually 1000/longer frametime = fps - not in this case? What do the red spikes represent?
Frame time is different from fps. Frametime is the time to render one frame. But here, i talk about frametime as a simplification. In this case, the graph shows the time taken by the mainthread to treat all the tasks it has to treat, i guess. When it is green, it’s OK, the Mainthread has not exceeded the budget allowed for it. When it is red, this means it exceeds the budget. In this case, it is maybe only a treshold (when the mainthread exceeds a certain time in milliseconds, it is red, whereas it is yellow, then green). In the graph, there were red spikes, which means that in some frames, the mainthread took too much time to treat all the tasks it had to treat. Why ? I don’t know. Maybe a checking loop that takes too much time (for instance, checking the airport aerial zones for communication: if those zones overlap, maybe this could lead to algorithm issues, with some cpu overloads). Those spikes have been removed from the last update fix in my case, and in the location i have tested.
I noticed the following:
When flying low over a certain kind of tree forest [usually on the US east coast], my RTX 3070 bottoms out. Once I pass the forest, the GPU normalizes, but then the mainthread slows down for 5-15 seconds. It’s almost the the GPU and mainthread have to resynchronize after the GPU gets overwhelmed.
Anyone else who has experienced the same issue?
CPUs bottlenecking so gpu is idling, hence the stutters. idle gpu = runs cooler ..
Thank you ! 
If you like, you can try the Remove Trees mod and take a flight around the area where you have stutters. For me, this mod helped to eliminate severe stutters at certain forest areas around Mount Rainier. It doesn’t look too bad without the trees, and you won’t see that ugly lowered trees draw distance anymore.
https://www.flightsimulator.blog/2021/04/03/performance-boost-tricks/
Thank you, setting tree detail on low seemed to do the trick. I’ll check this out too.
Frankfurt and some of the handcrafted if you get low performance which I taught was a vram issue but they are still not well optimised.Only shows 7.0vram out of 8 on my card and the performance is still quite bad including Paris LFPG.Looks like its on going progress.
Heathrow runs way better.
It was relevant to me as to my prior exchanges with others and what has improved my performance since the 1.15.5.0 upgrade.
If I am missing something I will be happy do delete or move my post.
Take care
Post has been removed.
Take care,
Flight Simulator surely has a memory leak. Tonight I flew for a few hours with @FlyingCookie650’s Thursdays weekly event and after that I decided to do a few Landing Challenges.
After a while I started to get stutters. I lowered the Global Resolution and still continued to have stutters.
I started task manager to see what was going on and this is what I saw. It had 19.6GB active and 64.2GB of Committed SRAM. Even though I have 64GB of SRAM, we are now going into paging and Flight Simulator at this stage, when I’m just doing Landing Challenges, should not have 64.2GB of committed SRAM. Besides FSXX I also have other things running in that background that require SRAM.
This is definitely a memory leak and something that hopefully gets fixed in the next update.
After I went back to the main menu, it got even worse. Active SRAM to 23.1GB and Committed up to 69.4GB
And later it went to 1fps.
omg.. such high amount of memory allocation I’ve never seen. Can you also summary when that happens ( only in the Landing Challenges ?, scenery, location, airplane model ) ?
A memory leak is it in case these allocated memory will never be released. I seen commited usage of 40-50 , but only short time over cities like London and if I leave that areas, the memory becomes free.
That the memory usage made trouble, started earlier.. it comes more and more on top with the 1.12.. for users with 16GIG RAM and with 1.14.. also the users with 32GIG RAM report issues ( need increase pagefile ).
EDIT: I remembered me at a post from @SvenZ 
Reducing Terrain detail to 10 for a while usually gets the memory to go back down, but you can’t increase it back over 200 without leaving the sim. Not an option if you fly with LOD over 2.0.
Pausing helps as well. Go make a cup of tea, have a sandwich, come back 15 minutes later and see if it has released all that memory.
Reducing sim rate helps with the memory blow up, Increasing sim rate makes it worse. Movement over the map is a big factor in something falling behind and not letting it go when you’re already out of range.
I first encountered that when I still used the rolling cache, flying over PG areas was fine, leaving them caused slow down. All that PG data stayed in memory and slowly (too slow) got written to the rolling cache. No rolling cache solved the slowdown and memory increasing.
However since the last update, whatever cleaning up process there is, seems to have gotten a much lower priority. Leaving stuff in memory that should already be gone. It should however get released when you go back to the world map, or maybe it still hangs on to it until you exit the sim. Exiting can take a long time when it gets in such a high memory use state. (Since I don’t use rolling cache I simply end process now, logbook won’t get updated but that’s a mess anyway. Windows recovers the memory instantly, restart sim fresh)
I was under the impression that it was slowing down once all the texture had finished loading. Once all textures had loaded, the GPU had more to process. Following that reasoning, I would think the textures would load faster with rolling cache; hence the GPU load would increase faster and the sim would slow down sooner…
But I have no idea what’s going on.
Another thought is the VRAM is running out, due to a lack of software optimization, and the bottleneck becomes system ram.
I have a 3070 with 8GB of ram.
Flights are flawless in most areas, but the wooded area near Manhattan brings FPS to low 20s
It depends whether you are CPU or GPU limited. Most of the time the CPU is the bottleneck. I can run at 150 render scale without losing any fps compared to 100 render scale.
Every time I turned on dev mode when this memory problem came up, vram was never an issue, at least not according to the game.
It does happen sooner in heavily wooded areas. However that is not textures or all that much work for the GPU, it is a lot of work for the terrain generator. It has to populate each tile with trees according to where trees are supposed to be. Perhaps something slows down when cleaning up the trees again.
Maybe volumetric clouds are another resource hog that doesn’t get cleaned up fast enough behind you. I’ve had the problem over open ocean, everything on low or off, just live weather, flying through clouds and fog.
The way the terrain is prepared can use a lot of optimization. I made this video 10 days ago, jumping back to the drone camera from far away (left it sitting there) to see how FS2020 loads terrain
