What's Your Frame Rate? - Part II 

Performance, frame rate, smoothness, fps—whatever you call it, it's a hot topic of discussion for our customers when running Flight Simulator X. In Part I, we talked about performance, and gave some background on the tradeoffs between graphics quality and frame rate, and linked to a Learning Center article about adjusting display sliders to customize your experience.

In this article, we're going a step further to offer some more specific tips on configuring your PC and FSX to get better performance. We're working every day to find ways to help our customers get the best possible Flight Simulator experience, and we plan on providing updated information and continued support via this site as our investigations continue.

In the meantime, here are a few things you should consider in the quest for the best FSX performance possible on your PC. This list is by no means exhaustive, and it may not include much new information for advanced users, but it should provide a good foundation.

Clean Up the Environment
The first thing to do when tuning FSX for performance is to consider everything BUT FSX—specifically, your PC and its component parts, including hardware and software. As we discussed in Part I, Flight Simulator has always pushed the limits of PC capability—it's no secret that it can tax even very powerful PC's.

Defrag! Defrag!
The files on your computer's hard disk (programs, documents, etc.) becomes fragmented across the disk over time. This can have a dramatic impact on your computer's overall performance, as it takes longer for Windows or an application to read fragmented files. Use the built-in Windows defrag tools built to defragment your hard drive(s) regularly. If you haven't done it in a while (or ever) you'll be surprised at how much faster everything runs—including FSX.

Keep it Clean
The more programs your computer is running at one time, the slower it runs. Shut down any non-essential applications while FSX is running. Check the System Tray on your taskbar and the Windows Startup group for programs that run in the background (which may not be obvious). You can also use the System Configuration utility to get a comprehensive look at programs and services that are loading each time Windows boots. This utility also allows you to selectively and temporarily disable most programs and services, so you can experiment to find the cleanest usable configuration. To use the System Configuration utility, click Start, click Run, then type msconfig and click OK.

There are other utilities available online that offer greater degrees of customization for advanced users. FSAutostart is a good one to try, and can be found at various Flight Simulator community sites using a search engine.

Excellent Drivers
You should install the latest drivers for your PC's components, which you can get from the component manufacturers. For Flight Simulator, pay special attention to drivers for your video and sound cards. Video drivers tend to be updated frequently, and the newest isn't always the fastest. While it's good to be current, don't be afraid to experiment and go back a version or two. Keep your motherboard chipset and CPU drivers up-to-date as well.

Captain Video
Current-generation video cards have settings for a number of features including filtering and anti-aliasing. Generally speaking, we recommend that you set these to "Application Controlled," and then enable their equivalents in FSX Settings.

Setting the Sliders
While Flight Simulator X establishes baseline graphics and detail settings based on your PC hardware's capabilities, most users find that they want to customize and tune the experience to a greater degree, based on their personal preferences. For an overview of how we establish these settings, see What's Your Frame Rate, and for a basic look at adjusting display settings, see Optimizing Visuals and Performance.

In this section, we want to briefly point out and discuss a few of the display settings that can have the most dramatic impact on performance. The following sliders, on most systems, represent the most "bang for the buck" when it comes to trading visual complexity for frame rates, so experiment with these settings first:

  • Autogen Scenery
    This slider controls automatically-generated scenery objects like generic buildings, trees, power lines, etc. Flight Simulator X is capable of drawing more of these objects (and in much greater variety) than previous versions, but it comes at a price—the more objects that are drawn on the screen at any one time, the slower the overall performance.
  • Traffic
    As with Autogen Scenery, drawing road, sea, and air traffic can add dramatically to the load placed on your PC, and decrease Flight Simulator X performance.
  • Bloom/Water Effects
    These effects make the sun and the water look dramatically better and more realistic. To this end, both bloom and the more advanced water effects require what's called "multi-pass" rendering. In other words, key elements in the scene have to be rendered (drawn) twice. To increase performance, try turning bloom off, and adjusting the water effects slider to lower levels.
  • Level of Detail Radius
    This setting defines the size of the area around the user in which higher-detail terrain mesh and textures are loaded. At higher settings, distant terrain is drawn in higher resolution with crisper textures, but this also increases load times and memory usage, resulting in lower performance.
  • Mesh Complexity
    Objects rendered in 3D are ultimately made up of a series of triangles. This slider controls the number of triangles that are used to display terrain. The more triangles, the smoother the terrain—but the greater the impact on system memory and frame rate.
  • Mesh Resolution
    Similar to Mesh Complexity, this setting affects terrain details. In this case, it actually defines the fidelity of the terrain to load from your hard drive. The higher the resolution (the further you set the slider to the right), the better the terrain will look, but, as with all the others, this also affects performance.

Saving Display Settings
One of the most useful new features in Flight Simulator X with respect to tuning settings for visual quality and performance is the ability to save and load those settings as configuration files. This makes it very simple to experiment with different settings and compare results, switching easily among different configurations. On the Options menu, point to Settings and select Save or Load.

.CFG Tweaks
For advanced users, there are settings that you can edit or add to the main FSX.cfg file. This file can be found by default in C:\Documents and Settings\Username\Application Data\FSX. The Application Data folder is hidden by default, so you will need to set Windows to show hidden files and folders. Once you've found the FSX.cfg file, make a backup copy, then you can edit it with a text editor such as Windows Notepad.

The FSX.cfg file is divided into sections, each one identified by a header in square brackets. For example, "[MAIN]" is the header for the "main" section. You can edit the lines following each section header in the FSX.cfg file for better customization and performance tuning.

Here are some settings that you can tweak to improve performance:


This setting, which defaults to a value of .33 (33%), defines the percentage of each frame that is devoted to loading scenery. Increasing this number can reduce "the blurries" and improve smoothness, but it can also reduce the overall frame rate.


This setting establishes the amount of video memory devoted to caching 3D models. Higher values increase frame rate smoothness and reduce the need to reload 3D models when rendering a scene, but may also use video memory that is needed elsewhere. The default value is 1000000.


In the real world, the further an object (an airplane, building, etc.) is from the viewer's eye, the smaller it appears to be. In Flight Simulator X, by default, if an object gets so small that it would take up less than 1 pixel, then the graphics system simply doesn't draw that object. By changing this value to a larger number, you can reduce the number of objects FSX renders in a scene and increase your frame rate, but it can also mean that parts of aircraft or buildings will disappear when they should still be in view.

We hope this article has provided some ideas that will help you get the most from Flight Simulator X. We're continuing to investigate customer feedback—especially regarding performance—and constantly looking for ways to improve. Keep an eye on the FSInsider site for further updates.