RollingCache revisited, essential with aggressive culling, or set "Terrain Pre-Caching" to Ultra

ok, do u know why manilual cache is not selecteable, it’s grayed iut

Good post, OP. Thanks! Rolling cache previously seemed a no no since people were having issues with the cached terrain prior to SU5. But now, it’s back on!

1 Like

No idea. It allowed me to try to use it pre SU5, but no matter what I did, always CTD when trying to download an area. I haven’t touched it since.

Thanks for the advice.

Having the rolling cache on an good nvme ssd is almost as fast as shown in the second video.

But as long as the ram usage is stalled by the game itself an ramdisk is an very good idea. I never mind that this classic would become important once again. I think the last time I used an ramdisk was on my Atari falcon (I owned the 14MB RAM card so I could allow myself that :grinning_face_with_smiling_eyes:).


That’s an interesting idea to use the leftover ram as your rolling cache. I also found that rolling cache is necessary now, but how easy is this to set up? Would it be possible to get some more detailed steps on how you set that up? Hopefully I’m thinking it’s harder than it actually is :grin:

Simple, download and install ImDisk

That puts two icons on your desktop, double click the one that says Configuration

Select the size you want (select GB first) and leave the rest as is. Drive letter R: is the default but you can change it. Don’t turn on compression, just adds CPU time and leave the bottom check mark on.

Click OK and this pops up
You can close that, it’s just standard drive information.

Then go to general options → data in game and set R:\TEMP as the path to use

Since the game uses GiB, while windows uses GB, 4 GB of RamDisk is smaller than 4 GiB of rollingcache, hence I type 3.8 there. That makes a 4 GB rollingcache in R:\Temp which is more than plenty for looking around while flying through a PG area. However you can make it as big as you’re willing to ‘lock’ system RAM.

And that’s all there is to it.

When you unmount the ramdisk you get the option to save the contents (to mount again later) however I just let it go, start with a fresh cache after a reboot. I just leave the ramdisk going, it’s not taking any resources apart from a bit of RAM. (It shows up as System in the performance monitor)

Starting the game without the ram disk mounted simply gives you a message at startup that the rollingcache is disabled.

Starting the game after clearing the ramdisk also disabled the rollingcache with this message
Simply go back to options and set it at 3.8 again (or whatever value worked with the size you made it). I guess the game rounds it up when creating a new rolling cache. However as long as the ramdisk stays up you can exit and start the game as many times as you want and it will continue using the rollingcache as created.

Btw if you look at the drive it will show ROLLINGCACHE.CCC just like any other file

All very simple, no crashes, has been working very smooth for me since I first used it.


Thanks for the detailed guide! That makes a lot of sense, and I’m definitely going to give this a try. Just makes so much more sense than putting the stress on the ssd, especially with 32gb or ram.

1 Like

Thank you for the detailed and helpful instructions.

While checking the 32Gb memory utilization I see that other then MSFS there also a bigger reserved allocation and thus the free memory is like less than 30 - 40 %. And this seems to fluctuate.

My question here is does that mean when the free memory gets to 0 anything else will then be on the physical page file? I’m quite hesitant to have that happen.

Any advice?

Windows 10 will use the remaining memory for cache (standby memory)

So it always seems free memory is very low.

The game uses very little now

(System PID 4 is the RamDisk)

The reason to keep memory use under 50% is to stop windows from using the pagefile. Any inactive memory gets paged out when you use more than 50% of your RAM (windows 10 behavior, can’t stop it apparently). Hence I keep the ram disk small to stay below 50% even with tons of tabs open in FireFox.

It won’t matter for rollingcache though since that’s always active and won’t be paged out. Just less used browser pages and inactive memory from FS2020 might be paged out. It’s not really an issue until you get close to full utilization of your ram.


Thank you very much. Really appreciate your help.

1 Like

Sorry not very savvy with all these…What is the difference between these additional steps vs simply turning on the rolling cache in the in game menu and select a path to be one of the harddisk available? E.g. C:?

Or anyone can help explain?

1 Like

Yes I second this. Thanks for the great explanation so far but could you add why it’s better than the default rolling cache? I had the same experience as the OP with the culling/constant donwloading so I just enabled rolling cache and gave it 20 GB and figured I wouldn’t had to look at it for a long time. Any better suggestions though are welcome.

@SvenZ great posts - thank you

Bandwidth for download at all right now seems to be an issue for me - I do wonder if the servers are struggling under the load of the new xbox player base. I also wonder if the new approach from Asobo means much more data is being downloaded per player for the reasons you’ve highlighted and I wonder if this is something that has been an unintended consequence of SU5.

Anyway, giving this a try to see if it improves things. Loading over Paris last night was awful.

@SkyVagrant4490 - the idea here is to store the rolling cache in memory and not on disk. That makes it much faster to access and less strain on the disk - SSDs do have read/write lifespans, although I don’t know how much strain using one for the rolling cache really is. So it should mean that when the rolling cache is used to show scenery, it will be much faster loading than disk or internet/redownload.

@BafflingBerry63 - as above - this is functionally identical, but should be much faster than loading the cache from disk. I would especially not recommend using a physical hard disk (HDD) for the rolling cache as that will be slower than SSD. So in order of speed we should have: RamDisk faster than SSD faster than HDD faster than redownload - but that last will depend on bandwidth and servers.


Ok. I just check my c drive (OS) is an SSD and my other drives are HDD. Though cant tell whether redownload for my case is faster or SSD… maybe will try it out using both and compare which is faster…

Yes, just give it a go and see if there is an improvement either way

See the two videos I posted in the OP. That’s the difference between redownload (first video) and fetching it from Ram Disk. Rolling Cache on HDD/SSD will be in between those two scenarios.

Redownload is never faster.

Internet speed is up to 150mbps depending on your connection yet heavily depends on your physcial distance to server, congestion (prime time slow down), ISP capping your bandwidth or the server capping the upload. Plus downloading has the highest latency as in the slowest response.

HDD read speed is between 640 mbps and 1280 mbps with around 9ms response time (seek time) It’s actually possible to have lower internet latency yet consistency is lacking when it comes to internet traffic.

SSD read speed is up to 20,000 mbps (2.5 GB/s NVME speed) with avg 0.12 m/s response time, however write speeds are much slower, and it depends on how the file is accessed. Lot’s of little reads across the file are much slower.

Here’s the difference between HDD and SSD on my system

Reading the whole file in one go in the most optimal way gives you the full speed of SSD, However the rolling cache is accessed by tile (squares updating around you), little reads all over the place at best you get the 6,500 mbps figure (788.5 MB/s)

RAM transfer is between 50,000 mbps and 140,000 mbps with avg access time of 0.0000014 ms. The only thing slowing it down is if windows pages out the memory to its pagefile. Hence I advise a small ramdisk and rolling cache file to have it stay in memory and avoid using the pagefile. (Which should be on SSD, so you at least still have the benefits of SSD speed)

@gordongreig I also suspect that the Azure text to speech regularly switching back to offline voices is due to it getting bombarded with 'please expedite your climb/descent" all day long. SU5 brought a ton more unnecessary traffic on top of a lot more players.


If MSFS downloads at 50 Mbit in average and you fly 4 hours per day it’s roughly 8 Mbyte * 4 * 3600 = 115,000 Mbyte ( or 115 Gbyte) per day. In 9 days it writes 1 Tbyte to the SSD. That’s 3 Tbyte per month and 36 Tbyte per year.

Let’s assume you have a 1 TB SSD with a TBW of 360 (this means that at least 360 TBytes can be written to the drive) it is supposed to last 11 years minimum. Of course it may last much longer.

1 Like

So quite a long time then! I doubt I’m doing anything like 115Gb a day on downloads through MSFS.

Depends which aircraft, which altitude and where you fly.

1 Like

This shows MSFS downloading data at ORBX LOWI.