Improve FSX Performance With These Tweaks


Blurry textures, low frame rates and out-of-memory issues. Each one of those will be well-known to FSX users. There is one ‘easy’ way to be able to run FSX at maximum scenery settings without suffering a performance hit: spend thousands on a mega PC.

But as 99.99% of us cannot do that we need to find a compromise between quality and performance. However by spending a few minutes reading this post and applying some simple tweaks, you should be able to get FSX running beautifully on your machine.

I’ll state now that I do not claim responsibility for these tweaks, they are just the ones which I have found and used all bundled together.

First of all, my system spec is quite good, but by no means spectacular:

  • Intel Core i7 2600k 3.4ghz processor
  • NVidia GTX570 graphics card
  • 8GB DDR 1600mhz RAM

I also take no responsibility for any problems which may occur on your system should you apply these tweaks. As with everything, create a system restore point and back-up your fsx.cfg file before doing anything.

Please read all the post once or twice before making and changes!


The file is located here: Desktop\[USER]\AppData\Roaming\Microsoft\FSX

If you cannot see it you will need to show hidden files and folders in the folder options

Step 1

Open FSX and adjust your settings to how you would like – remember to be realistic given the spec of your PC. Save these settings.

Step 2

For a quick fix, visit this website – – and let it adjust your fsx.cfg file. You can now either leave the cfg file as it is, or apply the following:


Other than AI the biggest performance killer in FSX is the autogen. Even at its lowest setting the autogen is more dense than the highest setting in FS9. But you can still limit how much autogen FSX displays in a ‘cell’

Search for ‘TERRAIN_MAX_AUTOGEN’ in the fsx.cfg file and change them to the below.


By default I believe that these are set to 4,500 and 3,000. You can change them to different values if you like. The maximum value is 6,000 and use 10 as your minimum value


Search for ‘HIGHMEMFIX=1’ in the [GRAPHICS] section of the fsx.cfg file. If it’s not there add it.


This is something that will stop FSX freezing/crashing/hanging when you switch around the cockpit via mouse clicks i.e Right click –> change view to overhead panel etc… Read this forum post on AVSIM which explains what to do (you will need to be a forum member). Since installing this fix I’ve not had FSX crash on me when changing views. If you cannot view the AVSIM post try looking through these links


Make sure that your paging file size is correct, and if possible, set it to be on a drive that doesn’t contain windows and/or FSX. This article on the Microsoft website tells you how to do it (for Windows 7). I’ve read that a good value to have is 1.5x your RAM. So in my case it is set to 12,000mb (12gb)


This fix was only given to me recently and it still unknown to some people. The person who suggested it used to work as a Microsoft Partner.

1). Click Start, type regedit in the Start Search box, and start the regedit program
2). Locate and then click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems
3). (It is advisable at this point to export the key as it stands, just in case you want to revert to it afterwards).
4). Right-click the Windows entry, and click Modify.
5). In the Value data section of the Edit String dialog box, locate the SharedSection entry (you’ll have to scroll left and right to do so), and then increase the second value to 20480, and the third value to 1024. Be very careful not to change anything else, though (see 3, above, just in case).


This is a tweak to make your textures sharper in the distance. The FSX default is 4.50, I’ve seem some people report that they have theirs set to 8.50 and other folks claim that going above 6.50 is bad news. The LOD_RADIUS can be found in the [TERRAIN] section of the fsx.cfg file. I have mine set to 4.5 at the moment and it seems fine. You may wish to increase it if you want the sharp texture radius around the aircraft expanding – although this will lead to some sort of a performance hit.

Note that what ever you set this to, it will default back to 4.5 each time you enter, and confirm, in the fsx settings window. Hence why I said change your settings to begin with. You’ll need to manually change the LOD radius each time after you make a setting change.


This is found in the [GRAPHICS] section of the fsx.cfg file and by default is set to 1024. This is the maximum resolution texture that FSX can load. There are some add-ons that now use 4096 resolution textures (e.g REX 4), so changing this setting to TEXTURE_MAX_LOAD=4096 will enable the HD textures to load. It will not change 1024 resolution textures to 4096, but it will allow 4096 to load if they are present. Be aware that the higher resolution textures will cause a performance hit.


Find the [BufferPools] section of the fsx.cfg file and make sure that ‘Poolsize=0’ is present. You will also need to change your water textures in the FSX settings to High 2.x or higher or you will get flashing textures.


This is a tweak for Quad Core systems and it moves FSX onto another core.  Search for ‘AffinityMask’ in the fsx.cfg file and for a Quad Core  NOT running hyper threading set it to 14, for a Quad Core running hyper threading set it to 84. Read this webpage to find out if hyper threading is enabled on your machine.


Under the [DISPLAY] section in the fsx.cfg look for TEXTURE_BANDWIDTH_MULT and make sure it is set to 40. If you’ve not made any changes to the .cfg file before it should already be at 40 by default.


There are lots of arguments for and against using external FPS limiters. I used one for a while and if anything it made FSX more unstable. Under the [DISPLAY] section in the fsx.cfg file change UPPER_FRAMERATE_LIMIT= to your preferred frame rate. I use 30 and FSX runs at 30fps constantly. Combined with the BufferPools tweak this gives very smooth performance


This is a tweak that determines the fraction of the CPU time given to the scenery loader in relation to the time spent rendering the scenery. This is about finding a balance to between better FPS at a risk of blurry textures (lower value) and better scenery and lower FPS (higher value). The default value is 0.33 but I’ve seen a lot of people report a value of 0.10 – 0.25. If you are using the ORBX sceneries I’d go with 0.20 or higher (I use 0.20). Search for FIBER_FRAME_TIME_FRACTION= in your fsx.cfg file and make the change


As mentioned further up the page one of the biggest performance killers in FSX is the AI. Personally I don’t think that the ships, cars, ferries & vans whizzing around the scenery add much to the experience other than to degrade it, so I move those sliders to 0% in the settings menu. If you fly predominantly online then AI Aircraft won’t be an issue but if you want to have AI aircraft in FSX I would strongly recommend buying Ultimate Traffic 2 from Flight 1 and setting the FSX AI Aircraft to 0%. Because of the way that UT2 injects the traffic into FSX the performance hit is a lot lower than allowing FSX to use its own method of traffic generation. Basically, UT2 injects the traffic outside of the fsx process.

So there you have it, a long list of tweaks to help get the maximum performance from FSX. Before making any changes make sure that you have backed up your fsx.cfg file and saved it somewhere else. If the worst does happen and you don’t have a back-up, simply delete the fsx.cfg file and re-load FSX. FSX will create a new one when it loads. The down side is that you will have to apply the tweaks all over again.

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