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Tweaking FSX BUFFERPOOLS For A Smoother Flight Sim Experience

Last updated Sat, 15 Apr 2017 17:12:47 GMT
Originally posted on Sat, 15 Aug 2015 19:00:00 GMT

For anyone who has spent time using FSX in the past, you will no doubt realize that there is a fair amount of editing and tweaking that can be done in the background. In fact, this is part of what makes the simulator so incredibly popular for most people – it’s got such unique dynamism about it. 

Got a problem with how it’s running or something that has not been included in the base simulator? Well, there’s a good chance someone out there has made a professional standard of mod for just what you are looking for.

This is the perfect way to get you moving forward to where you want and need to be with the simulator, but the problem is that understanding it all and making those changes without at least some kind of professional help and input can be a little bit of a challenge at times.

If you are looking for an easy way to get used to these kind of changes and plans, then you need to start reading around and looking at the various options that are open to you. Every little line of text in the FSX config files changes something and many of them can make quite drastic changes to the overall performance – and looks – of the simulator if you can manage to find the right changes to make to get you moving along the right path.

One of the most common changes to make is to do with Bufferpools. They can be edited and molded to fit with your needs and requirements perfectly, and they ensure that the overall experience can be made to look smoother and much easier on the eye. The problem is that the change itself can be quite a challenge to make, and you’ll need to understand more about them to make changes.

Tweaking FSX BUFFERPOOLS header image

What are Bufferpools?

Have you ever noticed that the closer to busy and intricate detail that you fly, the more drawn in and challenged the performance becomes? It’s incredibly hard for a flight simulator to keep up with this change and development in graphical density in a dynamic format, and therefore it can cause a bit of a serious slowdown as you fly.

Unless you are using something that is designed exclusively for full power gaming, you are more than likely not going to have a PC that is capable of managing the complete strength of FSX without some hardware adjustments.

That being said, many change ad additions can be made in the form of the FSX.cfg file. This is, without a doubt, one of the most important parts of flight simulation modification and getting it just right will make the aircraft that you are flying, and indeed the world around you, look better and load faster than before. The problem is finding the right way to reduce performance lag whilst maintaining a high level of visual detail – and for some people, the solution for improving their flight quality is to turn to the popular editing of the numbers under the [BUFFERPOOLS] section in the config file.

Since the autogen feature that comes in FSX has a default buffer of 4,000,000, you can see almost immediately from changing this number to something higher or lower has a drastic change to the overall level of detail that you are getting out of your simulator.

Changing this number to something else, typically, give you license to make some rather unique adjustments along the way that will make it so much easier to manage the simulators settings. Without a doubt, though, one of the biggest alterations will likely come from changes to this setting.

It helps to manage the buffer provided to your simulator as it can help you change the way that graphics are being drawn and manipulated. Instead of saving what has been, if you like, stored by the buffer, you make it easier for the hardware to work in the way that you had originally intended.

Changing this number higher or lower increases or decreases the overall dependency that your machine has on the graphics cards to provide the juice. At the lowest ratings – a 0 – this effectively means that your FSX is running everything entirely from the power of your GFX card.

What makes them so useful?

Naturally, the most useful addition that is brought to the table here is the ability to give people the help that they need in making the simulator far more fluid. We want to look at how you can achieve this, but it’s important to have the background information on the actual changes first – uninformed changes in a flight simulation config file is just asking for trouble! Therefore, knowing what you are changing and the expected changes that will come from this is going to be incredibly important, especially if you change something like the Bufferpools setting in here.

Typically, you will find that bufferpools are going to be managed so that you can help to do one of two things;

  • Decrease the number to make your texture buffer come entirely from the memory on your video card instead of anywhere else, or using any of the buffer that has been saved up. This makes a rather big difference to performance for many people but it can also produce serious spikes in performance at random moments so it’s a change that has to be considered and looking at quite closely before making any decisions

  • Your other option is to do the opposite – increase the number and take on more of a burden from the buffer instead of video card memory. This will make the game perhaps a tad slower (for some people) but it can help to make a very consistent and secure level of performance in comparison to if you were to decide to increase the number drastically

The most important thing that you can do with using the Bufferpools change is to make sure that you don’t hide and that you experiment as much as you possibly can. This allows you to really see the scale of the changes that are being made.

Another important factor is to remember that these are useful for finding a better level of graphical quality, at the same time. If you have a very high level of performance and can probably even use some extra memory elsewhere to put more into the graphical qualities of the simulator without hampering performance too much, then this is very much worth your while due to the increased level of potential that awaits you.

However the decision really does come down to the individual machine – it may help, it may not be enough to improve performance.

How can I use them to my advantage?

The first thing that you need to know about using bufferpool changes is that they are quite dependent on your system. If you are willing to make these adjustments then they can require a fair amount of juice from your system, and this can make it a bit of a challenge to put things into the right level of quality needed – you need to be able to work with a machine that has strong and varied hardware in each section.

Your processor, RAM, graphics card etc. all have to be up to a high standard to really get the benefit from this, if you are going for the visual point of view.

Make sure that you are using a high-end graphics card if you want to reduce the number in Bufferpools, and in return you will get a far crisper and more realistic look to the world around you. You will run into some severe problems with stability if you go too low for your card to handle, though, so be aware of this as it can be a big problem if you don’t monitor the issue – make sure that you do these changes with extensive testing.

Basically, the math here is that simply need to have more video memory if you want to take the number down. The higher that you go, though, you can probably start to notice performance improvements on lower-end machines. Just remember, though, that many lower end machines will simply not have the capacity to run FSX at high levels of detail without a large amount of changes being put in place.

If the machine is not at a high enough standard to manage FSX and all that it entails then making config adjustments is not going to make a considerable difference.

Instead, you should be looking to make an array of adjustments that will really help you sort the situation out – if you want to use these features to your advantage you need to be working with hardware that can actually take the hit in the first place. Make sure that you do this by picking up some hardware adjustments if need be – there is no point trying these tricks if you were struggling to run FSX on the more basic side of the settings as it can be hard to get the balance that a correct number in here can make.

Understanding Bufferpool Numbers

The first thing that you need to do before you undertake any of these changes, though, is to make sure that you fully understand just what you are doing to make these changes. The numbers and the variations that you might try within the Bufferpool section can be so different to what might be used elsewhere that you can find that knowing the basic routes and numbers that people will try for can be a big help to making the right call.

Finding that balance in numbers is so important here, and you will find that going with one of the following is going to be the most preferable choice for you in terms of seeing some genuine results.

Throughout the process you will be dealing with something known as Poolsize = X. The X is what you change and will likely be a specific number at present – you just need to change it to fit with anything that is suggested below as a potential route to go down;

Poolsize = 490000000

This change puts you right to the highest limit that most people are willing to go to, and will make a very big change to performance in general. However, it can make greenery and scenery in general go absolutely crazy – thing can start appearing as if they reach a way up into the sky, causing a rather distracting look. It’s one side of the spectrum that most users of FSX will avoid.

Poolsize = 39000000

This setting can be a bit like the above for some people, but the majority will find that this setting is probably their best bet at “happiness” within FSX. it’s got a huge amount of smoothness added to it and will make FSX run really well on machines that aren’t hooked up to superb graphics cards and the like.

However, from a performance perspective, many people found that this was probably the most enjoyable setting for them – we would probably recommend this for most people, it seemed to be the most accurate option. However, be prepared for stuttering in airports if you are on a lower-end machine – however, nothing can really be done about this if you want overall performance adjustments here.

Poolsize = 200000000

This poolsize is one that can be very good, but it seems to be almost dependent on the scenery type. Whilst some forms would load up and look absolutely spectacular, others were a shadow of their former – slow loading – selves. It might improve loading times slightly for some people but the overall look is very grimy and hard to actually stay with, we found. It seems to be a very selective setting that if you do find any problems with, will need to be adjusted once again. It’s a useful setting but don’t become overly attached to it!

Poolsize = 120000000

This was probably the worst setting that we have regularly seen offered by people as “the solution”. It’s very jagged and poor in performance and made no real improvements anywhere –things seemed to be so much more stutter than they were in the past which obviously kind of ruined the enjoyment of the flight. Worth trying out, we guess, but it’s one that we rarely see people – or ourselves – heralding often.

Poolsize = 0

Seen by many people as the go-to change that offers the insight and help that you need to make the changes as effectively as possible, this setting basically tells your FSX software to reserve no video memory whatsoever. Please note that by using this you need water settings to be at least 2X.

It creates very smooth level of performance but it can make the entire world a bit too distracting for some people – it has a tendency, on some machines, to leave what are known as “artifacts” behind which will make your entire viewing experience so much worse. If you use this, you need to have the right machine as it’s a real marmite change to go through; some love it, and many others hate it!  

The Process

The actual process for putting it all together and making this work for you is incredibly simple – you just need to follow some very basic steps and you will find that adjusting the number is going to be a whole lot easier. All you need to do is;

  1. Find the folder that you installed FSX to, and locate the file which is appropriately named fsx.cfg. This file is where you will find what you are looking to actually change
  2. Next, hit CTRL + F on your keyboard
  3. A small search prompt will appear – look for [BUFFERPOOLS]
  4. It should direct you immediately to what we want to change – which is under Poolsize = X
  5. However, it can be known as Usepools = X as well, so make sure you keep an eye out for this
  6. Now, you need to start making some adjustments and changes to the number X and whatever it used to be, try it out as anything that we have suggested above

You can look around online for other options but having tried these out on a whole range of different machines I would thoroughly recommend at last starting with the options that we have provided for you up above.

The process is far easier – you will need to keep adjusting and changing, though, until you find the number that runs most concurrently and accurately with your machine.

However, there is one thing that we must stress and that is the fact that any and all configuration changes you see online – for Bufferpools or otherwise – are utterly subjective. What works for your friend and their hardware is not necessarily what you need to put things right. No, you need to find the settings that work for you; even on an identical machine, other problems can pose themselves. It could be device drivers; it could be something utterly insignificant that you would never really understand!

Whatever the reason is, you need to make sure that you choose a style and a format of settings that work for you. It’s incredibly time consuming and you will spend more time going through trial and error plans than getting anything interesting to work, but the one thing you will most likely find is a suitable balance between performance and visuals. It will take some time, granted, but the reward is that you can utterly improve the level of performance within FSX by a considerable margin just by making these adjustments to the config file.

VIDEO: How to Tweak FSX Correctly (frooglesim).

The video below demonstrates how to tweak FSX correctly.  It also discussed bufferpools - it's a very interesting video to watch.

Additional Changes

There are many more changes that you can make to the program along the way, too, and many of them are found nearby and close to the Bufferpools section. We recommend taking a further look at these kinds of changes in the future as they can usually offer some very useful clues for what to change. If you are looking for a rough idea of what other parts of the config file may do, for example, you’ll find that various changes in specific areas will include;

  • Changing FSX to run on quad cores – this is done through the Jobscheduler section and should be looked into further if you are using a quad core processor

  • The maximum load of textures – If you change a feature called TEXTURE_MAX_LOAD to the value of 4096, you can get full HD textures. Keep in mind that this will dampen the overall performance level if you are not capable of such feats, so make sure that this is a service that you can actually benefit from

  • UPPER_FRAMERATE_LIMIT can be changed, too to make sure that you can get a quality frame rate. Many people will go with 30FPS by the way, as it offers a fine balance. If you find that things like Bufferpools aren’t making the solid performance dent that you hoped for, you can potentially smoothen the performance further by making a change to this setting as well

  • FIBER_FRAME_TIME_FRACTION is another hugely useful tool and can be used to help find a greater balance in your simulator between performance and style. Depending on the number in here – usually starting at 0.33 – you will find that changes up or down can help to make the performance more balanced at the cost of optimal graphical output – if you are not bothered about that, it’s a useful compromise to work with.

Just make sure all changes are made to a blank and new copy of the fsx.cfg file! 

You may also find our FSX Performance tips/tweaks article here very useful for improving performance.

Download iconDon't forget... We have a huge selection (over 24,000 files) of free mods and add-ons for FSX, P3D & X-Plane in the file library.  Files include aircraft, scenery, and utilities  All are free-to-download and use - you don't even need to register.  Browse on down to the file library here.

Ian Stephens

About Ian Stephens

Ian Stephens is a flight simulation enthusiast also with a keen interest in aviation and technology.  Ian spends a lot of his time experimenting with various simulator packages but has a love for Microsoft Flight Simulator X because of the huge selection of add-ons available.  However, Ian also has copies of Prepar3D and X-Plane installed. 

Ian has been writing for Fly Away Simulation for over 9 years.  Should you wish, you can contact Ian via email at


Leave a Response
Orion K. DaleyTue, 16 Aug 2016 23:14:44 GMT

Dear Ian -

I have enjoyed your articles on flight tuning. I am writing though about 'LimeRock4FSX' , where no real actual fsx.cfg tuning appears to be required, and was wondering if you would like to get in the drivers seat?

In late June, I asked myself, what does FSX have for Lime Rock Race Park? I flew there in a Beach from Sikorsky which is near where I live.

In FSX , there was absolutely nothing there. Having the habit of building things for where ever I go in FSX for the past ten years now, I decided to build Lime Rock and everything that had to go with it. So my wife said let's go visit there and take some pictures !

Frankly, I have never been into games, but simulation, absolutely. I also prefer the 'photo surreal virtual world' of FSX over my son's racing games when thinking of racing cars -

I reasoned that FSX first being a simulator, I could tailor cars the way I tailor aircraft as well as trains - I could make also really hot cars which also 'now finally have a place to go' !!!

Lime Rock 4 FSX I found Exhilarating while having a low foot print lets say compared to some CityFX package.

With Lime Rock 4 FSX, i discovered a lot of extra FSX horse power when not needing to eat clouds and land tiles, while coughing on Autogen for my old rig while collapsing from the Blurries.

With Lime Rock 4 FSX, LOD is of no consequence, and focus can be on the immediate virtual world and what you are doing at 190 MPH without OOM or FPS issues.

There is also no boat traffic per se, cars can be set low, and you simply do not have the time to look for air craft - well, that is if you visit as perhaps like some HAL like spectator in multiuser?

I hope you get in the drivers seat of many of the fine hot cars in the photo surreal world of LimeRock4FSX , and perhaps your team mates would be interested in joining you in multi-user mode -

Its totally free -

Best Regards,

Orion K. Daley

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