Severe Performance Problem in Identified and Reported

Earlier today a user posted a severe problem during a flight from KORD to KATL. Towards the end of the flight, the FPS dropped to about 2 or 3 seconds per frame making MSFS unusable. The user provided enough info about the flight for me to try it. I encountered the same performance drop near the same place. My screen was updating like a slow slide show. The decrease in FPS was almost instantaneous, no earlier FPS degradation.

I’m seeing many posts describing the poor performance since the update…

I’ve collected Windows performance information capturing about 30 seconds of activity. I’ve submitted everything I found to Zendesk with “Urgent” at the top. This problem needs an immediate fix! Can the moderators help escalate this?

If you are interested here are some of the details I found.

Task Manager showed flightsimulator.exe (MSFS) continually allocating memory. In other words a “memory leak” because MSFS was not freeing up any memory. The Working Set memory was increasing as well as Page Faults.

Looking at the Peformance Monitor and filtering it for MSFS, I saw that disk usage was high and the file with the highest byte count was c:\pagefile reading and writing about 4 to 8 Mb/sec. This is why the FPS dropped so quickly and dramatically. As the memory leak grew, all RAM was filled so Windows started allocating virtual memory which it is supposed to do. But the memory leak was growing faster than Windows could allocate more virtual memory. Windows started thrashing which means that it was using all of its resources to move memory pages back and forth from RAM and virtual memory. Very little resources were available for anything else. MSFS frame rate dropped because the thrashing was consuming everything.

I used some Windows tools to collect about 30 seconds of information while the FPS was so poor. The poor performance continued after stopping the flight and until I exited MSFS. I rebooted my PC to initialize the RAM and virtual storage.

I have not been able to perform an in-depth analysis on the performance data I collected. However, I found a stack trace showing one particular dll recursively calling itself. This could be the source of the memory leak. This is only speculation since I do not have access to the source code (obviously). All of this info was given to ZenDesk including the name of the suspicious dll.

If this memory leak is causing performance problems for everyone, the amount of time available to fly before performance tanks is determined by the amount of RAM that is installed. I had been flying for about two hours before the thrashing started. If everyone is having this problem, an immediate fix is needed!

I’ll post any info I receive from Zendesk, Asobo, or MS.


Looks good. Are you sure this is the problem?

I am having exactly the same slide-show issue. Since August, the first time I noticed this, has been after the March 9th update, on a short routine flight from KSAN to KNYL. This happens on a dedicated computer, not having any other software installed into. I don’t use mods, even to prevent such problems. Had it during climb out of San Diego, about halfway to Yuma and also on approach to runway 21R after having flown a DME arc from COVOK.

I didn’t investigate via performance manager, as after a day at work, I would like to fly rather than fixing new problems never existed before.

As a side note, I now feel quite unconfortable to invest lot of money on new hardware or add-ons, for a software that today works fine, but tomorrow not anymore. With the added risk that it will be fixed only after long time and, even after the supposed patch, it will not be good as before. This isn’t an occasional problem (which I can understand) but at every update, something breaks badly. It is a shame on a SO beautiful and innovative sim, which I still love. They should really consider a roll-back option to go to previous release (I really don’t like things that are too much beyond my control), or test the updates through a reliable beta channel.


Voted - would be interested in knowing name of .DLL and method used to identify it so I can take a look at my own system

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I encountered the Same Issue Landing at Venice. The Slide Show Issue lasted for around 5 Sec in which the FPS was 2-3 and thereafter regained, but the Performance degraded heavily from 45 FPS to 28 FPS even after regaining till Taxi to Gates. AIRPORT LIPZ, Zulu 08:21.


I can also report significant stutter/lag/jitter problems with MSFS 2020. Here is my rig which was bespoke built for MSFS 2020:

ROG STRIX X570-F Gaming
Ryzen 9 3950x (Over clocked AND not over clocked)
RTX 3090 24GB (Over clocked AND not over clocked)
32 GB DDR4 @ 3200MHz (also tried 64GB which made no perceivable difference)
2TB SEAGATE FIRECUDA 520 GEN 4 PCIe NVMe (Only Windows 10 & MSFS onboard)

All firmware and drivers are latest, up to date versions.

Over the past 3 months, I have literally tried every tweak and workaround in existence, all without success. (Also reinstalled Windows and MSFS from scratch after workaround experiments in order to erase any possible contamination from workaround changes). In frustration, I actually commissioned a Computer Scientist to examine my system and the stuttering issue itself. Following extensive investigation, his opinion was that the cause must reside within the source code as my rig demonstrated optimal performance results with no bottlenecking or overload issues.

My rig can comfortably run every hardware intensive simulation and game I’ve tried with 100% fluid frame rates and with all the bells and whistles ON (EG: Forza, DCS, XPlane). The only title with stutter/lag/jittter problams is MSFS.

I’m not going to enter a “You probably didn’t do this or should have done that or did that wrongly” circular argument here. When I say, I’ve tried literally every setting change, 3rd party SW tweak etc, that is a true statement. So there is no need to expand further on that.

I am only writing this now in the hope that either ASOBO or Microsoft will rectify this problem in the DX12 patch, or even before that time. In the meantime, it is such a shame that this beautifully stunning simulation has been rendered almost unflyable for so many loyal, paying Simmers.


Same problem here. Ryzen 5950 with GeForce 3070. 64GB Ram. 2GB NVMe. Non overclocked.
Before the update I could fly in the high 50s in autogen scenery. No stutters. Now I stll get FPS in the 50s as long as I fly straight. It doesn’t even need a larhe airport or photohrammetry havevthings go srewy. Even on going into a standard banked turn with the C172 Classic the frame rate suddenly dropped into the low 20s for no dicernible reason. Computer was only running MSFS. Before the update I was doing test flights regularly with Photoshop open while editing textures without any problems

I like this theory- but I wonder if it relates to my performance problems specifically around KATL (Asobo’s and Imaginesim’s as well), KLAX and EGLL. I have a ton of addon airports, but these three grind my system to a complete halt. If I’m anywhere in range of these airports loading, my system turns into a slideshow for up to a minute before resolving itself. It’s not helpful that it also happens on final…

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32GB of memory here, I too get good performance once I takeoff but soon after my cpu usage goes through the roof. I assumed it was related to the sim loading in the next scenery area as my memory usage never really went above 50%. Disabling my rolling cache didn’t seem to help the cpu usage but it did seem to smooth things out. Something definitely got messed up.


What I noticed is an high CPU % (98-100) near airports with ATC. I tried lowering every traffics to 0 but has no effects.

Outside ATC FPS and CPU return to normal.

GTX1080 water-cooled, i5-9600 OC water-cooled, 32GB, triple monitors 1680x1050.

I personally have not noticed this memory leak. Once RAM is allocated to the area that you are flying, it pretty much stays consistent. I have seen no paging on my system. I think about the most FSXX allocates is on average about 24GB.

I just flew from KJFK to KPHL in a Longitude. Committed memory in KJFK was 23GB, while in flight it dropped to 21GB and when landing back to around 23GB. Once I shut down and went to the the main menu, it dropped to 12GB.

I used the AP most of the way and did a visual into RWY 26.

Maybe this memory leak is only happening on certain planes.

@PacificSet90456 What plane were you flying? I can try with the same plane and see if I get the memory leak.

Same issue:
Aside from the usual stutters I had here and there before the Update my Sim started acting up yesterday going EGLL-EDDM.

I had about 4 freezes that lasted for about 10-15 secs. At first I thought it had to do with the scenery of London but it even happened on FL350 at night. Impossible to fly and Vatsim controller even saw me not moving.
Absolutely unplayable.
Specs are 5600X, RTX3080 and 32Gb Ram @3600Mhz

Even if that is not the solution, you did some fine super-sleuthing! Your logic sounds good to me.

Actually, there are about three dlls that are suspect that show up over and over. I haven’t had time to analyze all the threads and I don’t have the source code so I may be mistaken in which one is the culprit. I don’t want to post anything that might be misleading or cause anyone to do something before this is fixed. But clearly there is a memory leak that needs to be fixed as soon as possible.

This isn’t a graphics problem, cache problem, hardware problem, etc. There is no workaround that I know of.

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I found the reason for the FPS tanking so quickly after a certain amount of time. It isn’t a graphics setting or hardware. There is a memory leak. I’m surprised Asobo hasn’t found this. I have no idea how they do development and testing but they should have at least one pc dedicated to running the published update 24/7 to capture these kinds of issues.


Wow you are absolutely correct.My 32gb is nearly full!!! I just loaded up the a320neo @KATL

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It could be certain aircraft or certain locations or maybe a combination of both that might be triggering the memory leak. I think it is more time related and the amount of RAM. There are a huge number of posts describing the massive drop in performance and there doesn’t seem to be anything in common such as a particular aircraft, scenery, or add-on.

The memory leak was causing hard page faults with MSFS paging about 4 MB/sec.

If you want to attempt to replicate this problem, here is the IFR flight plan I used:


The initial info I was given was an IFR flight from KORD to KATL. The FPS dropped and the “slide show” started right before entering the ILS 26R approach.

Since the memory leak is time dependent on the amount of RAM, users with 64 GB of RAM may not see this problem as soon as everyone else. I have 32 GB and I was about 2 hours into the flight with a stock TBM 930 when the problem happened. Slower aircraft might see this problem earlier in the flight. Faster aircraft might be able to land before they see this problem.

Hi guys

I agree for the memory leak , try to fly around New York with Cessna CJ4.
After a while , it s completely unplayable for me.
My graphics card is only use at 20% and the memory (32 Gb) is almost full

I really really hope a fix soon cos actually , I have too many problems on high end rig (Ryzen 5900x , RTX3090FE , 32 Gb RAM etc etc…)

To the OP of this post thank you for your findings. My short testing. Loaded up a flight @KATL heavy stuttering 25gb of usage.
Denver 17.6gb butter smooth both used with the A32NX

I have this same issue going on. I can for sure see that it’s like a line gets crossed in certain areas. One side good, one horrible. even captured video flying in a circle as i cross this invisible line. I should get on uploading it. But, I don’t have a page file. I removed it as pointless with 64GB sdram. Have had actually, a really good experience until Su3. Now it’s unplayable. I also have seen msfs using 32GB+ sdram as of recently. Hope this information helps.