Long haul performance degradation back with SU12?

MSFS2020 Long Haul flight from Houston to Seattle in Headwind A330neo / 4K HDR - YouTube here, just as an example, my flight from today…

you see how nice the FPS are in the beginning and during cruise, it think it started going downhill from minute 48 onwards…

So I kind of went desperate in trying everything I could to fix the issue. I removed my entire community folder and started a flight from Denver and went straight north from there to fly over as much land as possible. After about 2 hours I had zero stutter frames in the high to low 60s. After this I slowly kept adding 5-10 more addons and then tested another 2 hour flight even testing with some add on aircraft like the FBW A320. After I finally got through my entire folder of add ons put back into the folder and did a test flight I had zero stutter again. This was with all community add ons installed. After testing again with all plugins I did a normal flight and I think one my big issues with the stuttering was the traffic injection with FSLTL and FSHUD. When I didnt have FSHUD running it was fine. When I did the stutter came back.

Hope this can help somebody.

EDIT: Just cancelled my flight in FSHUD and my frames came back instantly. Maybe its less FSLTL and more FSHUD.

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My two cents to add more support to what is already a clearly evident issue.

Flew from EKCH - EFHK. 1 hour flight, performance on arrivial had my FPS into the low 20s.

Main thread on parking at the gate is 35-37ms. Reloaded into the same gate, same time, same everything and I was getting 30-32ms main thread timing. This is a pretty low level example. Longer flights result in much bigger differences.

7950X3D, 64GB 6000MHZ Cl30 RAM, 4090

I guess we just have to wait and see if Asobo can fix it. It certainly doesn’t bode well for the introduciton of more long haul aircraft…

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this doesn’t seem to affect aircraft that use default systems such as the working title 787 avionics, Been flying 10-13 hours without a single drop in fps.

I had this issue wth PMDG 737, Fenix A320 and Ini A310

but not with Kuro 787 or Default 787-10

wonder there coming no fix for this fps long flight problem


Update for A320 Fenix available. EDDF on ultra settings is now possible.

Hey everybody, have you thought to check your VRAM usage with the dev FPS monitor? I think that may be part of the issue. When I pulled into the gate after back to back legs in the Fenix A320, I noticed my performance was noticeably worse than when I started.

So, I opened the dev FPS monitor and noticed that my VRAM was totally maxed out (9gb/9gb usable on the RTX 3080). I restarted the sim and started up at the same gate and noticed my FPS was about 10 FPS higher, and that my VRAM usage was sitting at only 7.5/9gb.

Seems like some of this performance degradation may be due to VRAM getting maxed out after a certain amount of time


Not the case for me. Only sitting at 7 Gn out of 11.5 available. So plenty of headroom

I genuinely believe it has to do with server tbh. MSFS is the only sim directly connected to servers at literally ALL TIMES. You can’t run this sim without having an internet connection. What makes me think this? I’ve used XP9-12 and p3d v3 and v4 aside from
The odd crash I did 12, 14, and 16+ hour flights and not a single time did I experience performance degradation. All of those outside of updates where basically offline sims unless you used vatsim it whatever. Again this is my theory on it but it’s about the only theory that makes sense at this point.

MSFS can run in offline mode, you just won’t get the online services (including the delivery of photogrammetry and high-res texture data that’s not stored on your PC).

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You cannot run this sim without an internet connect. Yes there’s an “offline mode” but if you per say wanted to do a flight while say out on a family farm where connection just is near impossible you can’t even launch MSFS

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Fair enough, the license check is lame at least on the beta (I haven’t tried non-beta with network off today). Though it’s a bit of a stretch to go from that to “therefore this is the precise cause of this precise mysterious slowdown that some but not all people see sometimes”.

I suspect the cause is rather more simple and involves leaking of generated objects that should get dropped out of the simulation over time and don’t. This would make sense, and doesn’t require any magic guesses about how networks could cause problems that don’t sound like network problems.

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Fair point. It’s the best I could think of though given this problem randomly comes and goes with no changes on the users end. I’ve literally changed nothing from the previous month (and I’m not on beta) and out of the blue perf degradation is back. After I had a whole month of doing some of the worlds longest flights.

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The reason I’m not convinced by the memory leak theory is that I can do the exact same flight with no changes to scenery/AI/weather and I get different outcomes (vastly different).

If it were a code based error, would the outcome change so much.

Some days I lose FPS (and the CPU/GPU usage tanks). Other days I end up with a blurry mess of textures. Then on the good days, everything works brilliantly. There is just too much variation for me to think it is anything else but server based

A few weeks ago this was fixed by disabling air traffic, boat traffic and car traffic. (airport vehicles can be left turned on)

I think that somehow the memory is full after a long flight. That’s why it stutters like hell after landing. But there are also players who don’t have this problem.

I think the folks who don’t have problems this severe are like myself… they have so much overhead with their system that performance impacts don’t equate the same way when comparing to someone with a more basic system.

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I’ve recently been getting an issue when flying on MSFS. Loading into the sim (usually fenix 320 or PMDG 737) I’m sitting at a solid 80-100 fps with my 4080 on TAA and frame gen on.

In the climb and cruise, all seems good.

Upon arrival to my to another airport - the frames and stutters increase. Dropping at least an average of 40/50 fps. I know this isn’t horrendous but it wasn’t happening before when i was first running the 4080.

Any suggestions?



I’m also having performance degradation after long haul flights (more than 4h). At the app phase FPS drops to 16-20 (i have it caped and tuned to maintain 30fps stable with the sim VSync), but when closed and started the sim again… same scenery, same everything but now 30 fps without any problems.

I don’t have AI or live traffic, or multiplayer. No ground aircraft, airport vehicle and worker to 30%, Land and sea traffic to 40%.

After 3 years of MSFS still a pain in the ■■■ trying to debug why the sim does this things

Closed as improved in Sim Update 13: Release Notes - Sim Update 13 [] Available Now

Note in the recent Developer Stream, this will continued to be improved in the coming Sim Update.