Memory leak on increased sim rate/slew mode

I’ve noticed a memory leak in the latest release that degrades my game play from about 30 frames per second to about 1 to 2 frames per second (at the end of a 4 hour flight).

Plane: Daher TBM 930
Route: Tour of large cities of Middle East (Karachi, Islamabad, Kabul, Dushanbe, Tashkent)
Settings: High Quality, 4k resolution, Live traffic, AI co-pilot on the radio, not developer mode
Mods: None
System: Intel i7, Asus 1080 Ti, 32 MB RAM

With each city I check my 32 MB RAM usage. It starts the first city at 30% and then by the last city it is up to 90%. CPU and graphics utilization at about 30% throughout.

Has anyone else noticed this frame rate degradation?

Just sharing this experience
As I was looking for some interesting places to fly, I used the slew mode and found an easy way to make evidence of memory leaks, that impacts also FPS

Note that in normal flight, I do not experience memory leaks

So here is what I did:

Start at an airport

I have my FPS, RAM and VRAM, GPU% counters on screen (I use the little Gamebar “Performances” window docked)
VRAM, RAM, GPU% and FPS values were all fine at the flight start

Then, I change to Slew mode (Y key) and start to fly at full speed (around 7400 kts) for a few instants (about 1000 NM) above some land

This way, the scenery could not load, because no sufficent time for it to load, so only a basic ground blurred sceney is displayed

Stop a few seconds sometimes to see how it gets

I noticed that:

  • VRAM filled up and stays full, normally it stays around 2/3 used
  • RAM (usually used at 50% of 32Gb) filled up and stayed full
  • FPS downgraded to a few FPS, and stayed at a low value. Note that GPU% dropped to a low value also, in concordance with FPS drop

When RAM and VRAM got full, the scenery did not load anymore when stop at some place

Then I observed in the Windows resource monitor, that RAM is freed with a very very very slow rate, it needed more than 20 minutes to recover a lower value, that enabled again scenery loading at the place I stopped
But FPS stayed low, as well as GPU%, never recovered

I’m wondering whether scenery loading fail, due to not enough time to load it (because moving, or if the connectivity with servers is not fast enough) could be at the origin of memory leaks (that are way too slow to recover), and induce indirectly a constant FPS drop with no recovery

When I fly “normally”, the scenery gets loaded sufficiently fast enough, and I do not experience this situation. But with the Slew mode full speed, I forced the sim to fall into a non-nominal situation, where scenery does not have the time to be loaded, and brings it into an incorrect state where it does not recover

I remember having read posts stating scenery with very limited LOD, and FPS drops, may be this could also be linked to this kind of situation

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Thank you for your contribution. It sounds like the same situation is happening for both of us.

I do not use Slew Mode, but I often change the Sim Rate to double or triple speed in between cities when I am at cruise altitude and on auto pilot.

I too notice the detailed textures and buildings are not filling in. Every texture tile is blurry. If I slow down the Sim Rate to normal speed, then I see the buildings and tiles fill in.

However for me, the RAM usage does not come down from 90% even if I just cruise at normal Sim Rate for 15 minutes and let all the textures catch up. Eventually the frame rate drops to 1 or 2 frames per second and the landing is almost impossible.

It sounds like we have a recreatable problem.

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I have experienced exactly this issue with advancing the sim rate. I suspect the slew mode and sim rate end up doing the same thing given the speed the aircraft is crossing the scenery - the sim can’t keep up and is continually loading scenery into RAM that it doesn’t then release because you’ve passed the area it was intended for. This is reacreatable.

I have only noticed this post SU3 though. Before then, advancing the sim rate did impact FPS a lot (the more the faster the sim rate), but RAM didn’t overfill and when you stopped advancing, it would return to normal once the scenery loading caught up.

I can work around this by watching RAM usage and stopping the sim advance before memory usage gets about about 28Gb (I have 32Gb). If I let the plane fly along normally for about 5 mins, the excess memory is gradually released. After about 15 minutes, everything gets back to normal. If I let the RAM fill up to 30Gb, I get the same issue as you and have to ALT-F4 the sim.

The scenery “catch up” has always been a feature for me with high sim rates - I think that bits normal. The memory filling up thing is new.

I have opened up a ZenDesk issue on this behaviour
https://flightsimulator.zendesk.com/hc/en-us/requests/98900

I will do one too when back at my pc

You might want to change the title of the thread to “memory leak on increased sim rate/slew mode”

Good suggestion. Unfortunately it does not allow me to change the title now.

You should be able to do this. If you click the little pencil at the bottom of your original post, you should get a view like this:

(this is from a thread I started a while back)

At the top, in the blue outlined box, is the title of the thread. You should be able to edit that

Roger Wilco

1 Like

LOL@ Space Quest reference.

But yes, same issue here. I don’t use Slew, but advancing the rate gets me blurry textures and unplayable frame rate by the time I am ready for landing. The frame rate doesn’t really recover when you back out the sim rate to normal. So I stay away from that feature for now.

1 Like

I encountered this problem the day after the last update. Flying from KORD to KATL frame rate dropped to about 2 FPSon the approach to KATL. I opened a ticket with Zendesk documenting the memory leak, even provided them with the name of a suspect .dll file causing the memory leak. After being open for 5 days, the ticket was marked “SOLVED” with the recommendation of a temporary workaround to set my LOD to 80. A statement was added that they are monitoring and investigating the performance issue an performance optimizations will be delivered in the near future. My “near future” isn’t the same as their “near future” because nothing has been delivered in the past two weeks. Also, I wasted my time telling them that a memory leak is NOT a performance problem but actually a code problem.

When ZenDesk marks something Solved it doesn’t mean the issue is Solved. It means it has been forwarded into the queue.

And where does it go after it is in the queue and how long does it take to move out of the queue?

That essentially means it’s moved to the development team to investigate. However long that takes.

I have no insight into Asobos’s Problem Management system. All I know is that my ticket is in the queue. I do not have any info that my ticket has been pulled off the queue and moved to the development team. There is no information if the queue is FIFO, LIFO, sorted by size or category. I have no information if the queue is 5 tickets deep or 50,000 tickets deep.

I had a problem. I created a Zendesk ticket. Zendesk replied. Conversation finished. I still have the problem.

I no longer care about my ticket because there is nothing I can do.

Last October, I opened a ticket about a different, unrelated problem. I actually received a reply acknowledging the problem and that it will be fixed but no fix date. That is the last I heard anything about it. The first thing I did after every patch or update was to see if my problem was fixed. The problem still is not fixed. I no longer check after any update or patch…

Patience. I imagine they have a LONG list of issues to work through and they have to prioritize them.

"We have recorded the bug you have submitted in our internal bug and issue tracker.

To understand what will happen next, visit the Zendesk Bug Reporting FAQ"

I experience the similar issue. Whenever I use the sim rate option, the fps basically dies… it drops below 10fps after coming back to the normal 1x rate from 2x or 4x etc. Sim rate used to be okay without any significant impact on fps, but somehow, after the recent updates, this issue has risen. I really don’t know why Asobo is not doing enough in-house test before they release any sort of updates. THIS IS REALLY FRUSTRATING. Can’t even attempt mid to long haul flight these days.

What I learned to do is monitor my RAM use with Task Manager. I have learned the keystrokes needed to peak at the RAM use: Open System Menu (Ctrl-Alt-Delete), select Task Manager (4 down arrows), look at RAM use (I set the RAM page to my default page in Task Manager), and close the window to return to the sim (Alt-F4).

I have 32 GB RAM. When my Sim Rate of X2 or X4 and the cities I visit bring the RAM use up to 60%, I slow the Sim Rate back down to X1. This lets the scenery textures fill in, and the RAM is reclaimed and gets back below 50%.

This works for me on long flights.