What and how does RAM impact performance in the sim_

32Gb are enough


With the way the sim behaves since the Xbox launch it won’t make any difference at all. The Sim has been re-programmed to minimise memory usage to fit in the Xbox resources. 32GB is way more than is needed to run MSFS now. The only possible reason to go for a huge amount would be to use most of it as a RAMdisk and perhaps put the rolling cache in it? But that’s pretty extreme


Oh, and we can all hope Asobo will provide us some options at some point so that we can exploit larger memory again to get better behaviours and performance.


Wait for WU6 where you will be able to re-enable the offscreen scenery caching that was removed in SU5, and see. I doubt going up from 32 GB will do any good though. Today it certainly won’t, I can usually not even get MSFS to use 8 GB of RAM.
I have 48 GB and upgraded for flight sim purposes, but as far as today’s MSFS goes that was a big waste. (I upgraded before the alpha even opened.)

That’s in WU6, September 7th.


Haven’t heard that this is going to happen. Was there something official about that or is it speculation?

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Official. First mentioned about a week after the SU5 release (can’t find that now; it’s mentioned in the patch notes or a dev update from around that time, that they were aiming for WU6), and then here:

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Ok thanks. In what way does the Pre-Caching influence RAM? I thought that was stored in the Rolling Cache?

32Gb of RAM is fine, and your 2080Ti has (I think) 8 or 10 GB of VRAM. Your current rig will do for a long time yet. If you watch Task Manager you can see the sim uses less than 6 GB of VRAM. That’s the one to watch. When the GPU runs out of dedicated VRAM it starts swapping to disk, and that can be a trouble spot.

I doubt it, that wouldn’t do much to reduce the stuttering. But they haven’t said explicitly what it is AFAIK.
Even on an SSD, loading from disk would probably be too slow to have it avoid stutter. I assume it will work the same way it did pre-SU5, i.e. RAM and VRAM usage will be higher (which is good!) with higher settings.

More RAM usage would indeed be good. It’s always best to cache stuff in the fastest medium and there is nothing faster than RAM (apart from the CPU cache of course).

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I run MSFS on Windows 10 Virtual Machine through KVM/VFIO/QEMU on a Linux host, with a Nvidia 2080 GPU passed through. I tested MSFS on different RAM configs even before SU5, from 16 to 24 to 32 GB. Even before SU5, the amount of RAM never seemed to be the bottleneck. When I ran it on a 16GB VM, MSFS used around 12-13 GB of RAM tops before SU5, After SU5, it never exeeeds 8 GB.

My personal suggestion would be to get faster RAM with tigher timings, instead of getting more RAM. Also, I think the GPU VRAM is more critical resource for MSFS than system RAM.

If you are planning to use it for VR, spend some good money on getting a CPU with very high single core performance, like 5800x or whatever Intel’s latest is. I personally feel a processor with more than 8 cores 16 threads is an overkill for this sim, as its diminishing returns beyond 8 cores. Again, this is based on personal experience after testing with different core configs assigned to my VM :slight_smile:


My understanding is that rolling cache is on disk, which contains photogrammery data that was streamed from Azure cloud. So ‘before and while’ you start flying, data needs to be fetched from Azure cloud. If you already flew there, this data is already in your rolling cache, then the game doesn’t need to fetch it from the cloud, as your disk is faster than the cloud.

The pre-caching that others speak about is when you are flying and the data has ‘already’ been loaded into RAM (either from rolling cache or Azure cloud), post SU5, some of that data is being removed from RAM, as a part of XBox optimization. Most PC users here have lot more RAM to spare and thus don’t want data to be removed from RAM, as it causes popping of artifacts during camera panning. Hope that makes it clear.

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ah ok. Two different things then. Thanks

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I have 64 GB of RAM. (i9-990K, Samsung 970 EVO Plus NVMe SSD)

I have no problems with FS2020.

4K at OBj LOD = 9 and Terrain LOD = 9.

Graphics are great with a GTX 1660 TI.

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I upgraded from 32gb to 64gn during the era of the great stutters.

The sim actually seemed more stable and I experienced fewer major stutters.

Some major changes were made to the way the sim handles memory in SU5 so I rarely see it use anywhere near my max physical memory at present.

However, I picked up a tip on these forums and I’m presently experimenting with a 16gb ram drive on which I run the rolling cache and it seems to work quite nicely.


Can you link to that tip? :slight_smile:

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64GB of RAM and an RTX 3080 on an i9 10900K… Well prior to SU5 MSFS was using 20GB of RAM. Now after SU5, the game now uses only around 5-9 GB of RAM. I do get a solid locked at 60fps even over LAX at night with Live Traffic and Weather. As soon as I increase the LODs above 2.0 the fps start to drop and I am CPU limited on two out of ten cores. This game really needs DX12 for better draw calls.

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But thats in 2D not in VR?

AND to run OTHER Apps at the same time on your PC, without causing MSFS to become starved of ram.