I know this is a known issue, but I was wondering if they are currently working on it. 

I just did a flight in the FBW from KBOS - KLAX. Takeoff and departure were totally fine, as should be. When I left for a couple of hours for lunch, during cruise and came back, the frames initially dropped while I started fussing around the cockpit, but then stabilized for the remainder of the flight. However, entering the the LAX area, below 10,000 it just became a slide-show. 

I can normally fly around the LA area without any issues. I fly all the time on ultra and my machine is a 3080 blah blah blah. Im just wondering if anyone knows whats causing this issue and if they are planning a workaround. 

My apologies if this has been discussed previously. 

https://forums.flightsimulator.com/t/decreasing-performance-throughout-long-flights-since-su5/441568?u=viralwhite

4 hours ago, Keirtt said:

https://forums.flightsimulator.com/t/decreasing-performance-throughout-long-flights-since-su5/441568?u=viralwhite

So I skimmed through that thread and there is literally no response from asobo about this major flaw... smh.  

not everyone has this issue.

it sounds like severe caching is going on then, could mean bad memory management is special cases, maybe only happens

with 4k?

5 hours ago, Keirtt said:

https://forums.flightsimulator.com/t/decreasing-performance-throughout-long-flights-since-su5/441568?u=viralwhite

More up to date

9 hours ago, Bdub22 said:

Im just wondering if anyone knows whats causing this issue

I certainly do not pretend to have a straight answer to your question, but a suggestion based on my own experience: My PC specs are much lower than yours (GPU 1070 no OC, CPU 8700 K no OC, most graphic settings on Ultra with AIG offline traffic 100%) and I do not have your problem.

As an example, I flew yesterday the FBW A320 Dev version from UUEE with DD airport and city scenery, to LEMD LVFR including city (more than 5 hours), hand flew both SID (in heavy overcast), and STAR with ILS at LEMD clear skies but located in a mountainous area - with no issue whatsoever.

My proposal: Use Add-on Linker and only activate those add-ons you need for your particular flight, this is what I have been doing until now. Try and see if this has any impact at all. If it does let us know, perhaps others could try the same.

They are working on it, insofar that they are trying to reproduce it -- but can't. They even have volunteers doing 24-hour flights who can't reproduce it. So, the issue may not lie within the sim. But they want you, those who are having this problem, to submit as much information as you can. What happens, when, under what conditions, times of day, geographical location (real and in-sim), departure and destination airport, VFR or IFR, plane used, add-ons used... Everything you can think of to tell them.

5 hours ago, Gelrd said:

More up to date

Ah thanks! That was actually the thread I meant to tag.

16 hours ago, Bdub22 said:

I know this is a known issue, but I was wondering if they are currently working on it. 

I just did a flight in the FBW from KBOS - KLAX. Takeoff and departure were totally fine, as should be. When I left for a couple of hours for lunch, during cruise and came back, the frames initially dropped while I started fussing around the cockpit, but then stabilized for the remainder of the flight. However, entering the the LAX area, below 10,000 it just became a slide-show. 

I can normally fly around the LA area without any issues. I fly all the time on ultra and my machine is a 3080 blah blah blah. Im just wondering if anyone knows whats causing this issue and if they are planning a workaround. 

My apologies if this has been discussed previously. 

What does Dev Mode show for MainThread in milliseconds at your departure airport?  KBOS is much easier to process than KLAX and the entire greater LA area around KLAX.  What I've discovered is this:   if your departure airport is less difficult to process than arrival it's critical to set departure airport MainThread to well under 20ms, to give major headroom for your arrival airport.  If departure and arrival airports are very very similar, then 20ms isn't a bad place to start.  Of note, Terrain LOD is arguably the most demanding on the MainThread.  Next comes Object LOD.  Perhaps after that the Buildings slider.  So simply get to your starting gate engines running, and open up DevMode and see where you're starting at and adjust as described above.  Here is an example of your flight, hypothetical because I don't want to stop my flight to find out right now:

At KBOS gate, all sliders Ultra, Terrain LOD 200, Object LOD 200.  MainThread is 19ms let's say.  I am very aware KLAX is substantially more demanding.  So I'm going to reduce both LOD's to 150, and reduce Building detail to HIGH.  Now MainThread ms is 16-17.  I've got some decent headroom and *should* be pretty good now at KLAX, if I guessed right.  I arrive, frames are solid but hints are showing that we may be maxing out the MainThread--meaning, we're likely to see MainThread ms now at say 23-24.  I come to a full landing w/o missing a frame, smooth, but by watching RivaTuner's OSD I can see CPU core running the MainThread is bouncing between 78-90 on occasion, but frames aren't quite being jeopardized yet.  

I think the situation is very different at departure when the sim is loaded up only w/ the departure area scenery.  I think over time and miles the loads involved absolutely are greater because it's keeping Boston area in memory while constantly adding new scenery.  But I do believe it does reach a steady state of sorts, so does not get 'worse and worse' over time, which I believe is part of the alleged issue with this.  I use 20ms as a rough standard to aim for to allow for sufficient headroom in case I misestimated the demands of the arrival airport.  My goal is to NEVER have to stop a flight at any point to make any adjustments.   I rarely have any issues with long flights at arrival airports by adhering to this formula. 

You might mention your hardware specs, at least your CPU/memory.

Addendum:  here is the short version of the above litany:  your settings are beyond what your system can truly manage from gate to gate.   It's easy to be fooled by this because your departure scenario, be at KBOS, or at KLAX as a starting airport will be easier to cope with than your arrival airport, increasing complexity notwithstanding.

Did your flight setup:

KBOS, Terrain LOD 200, Object LOD 200, All Ultra:  MainThread at 19.7ms.  I'll have no troubles departing here in fine shape.  My system will tend to be MainThread limited more than GPU:

Backed out to Main Menum then launched to KLAX same settings:  note MainThread now at 22.0ms.  I could takeoff here with very little issue most likely, but again it's virgin resource loading at departure:

Reducing both LODs to 150 now, and Buildings/Trees/Grasses to High from Ultra.  MainThread now down to 19.0ms.  We also need to try to accomodate the 'steady state' level of resources use, so really might like to adjust setting down a few more notches to get MT down to say 17.5ms to assure a smooth arrival, or something along those lines: 

To wrap up...if we did this flight in reverse, we would probably aim for starting KLAX at around 19-20ms and likely be fine at KBOS.  I really don't start feeling the beginnings of MainThread overload until we see milliseconds at say 24-25 or more.  But headroom is the name of the game unless you don't mind stopping and readjusting along your flights.  At easy to manage airports I might put Terrain LOD at 300 or even 400, but still follow the same logic to assure a smooth arrival.

Edited February 19, 20224 yr by Noel

I heard that after you experience FPS drops, if you exit and restart MSFS the FPS drops gets fixed.  So for example instead of doing 10 hours flight, do 1 hour flight and exit and restart and spawn back into the same location to continue on your flight    The question is why do you need to do this to fix the FPS drops on long trips. 

Thanks guys, and especially Noel for taking the time. You’ve given me some good places to look and actions to take.