Tuning Guide


Contents

The Prepar3D.cfg configurations file stores your simulation settings. It can be edited with notepad or your favorite text editor. The following entries are not written into the Prepar3D config by default, but may allow users to fine tune performance. There has been a significant amount of work done since Prepar3D 2.0 to reduce the need for these config tweaks, but the following tweaks should still work, and may help advanced users optimize their experience.

Editing Prepar3D.cfg

How to Make Changes to your Prepar3D.cfg Configuration File

  1. Locate the Prepar3D.cfg file
  2. Create a backup of the original Prepar3D.cfg
  3. Right click file and click "Open", "Edit", or if prompted choose notepad or your other favorite text editor
  4. Add the below text into the specific sections to make the desired change
  5. Save the newly updated Prepar3D.cfg and begin Prepar3D™

Below are entries to place in Prepar3D.cfg. They have the headings enclosed in brackets and the entries are bolded, followed by Performance Tuning Tips on the intended purpose of the fix.

[DISPLAY]

TextureMaxLoad=6

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

This can induce stutters. Use multiples of 3 only such as 3, 6, 9, etc. This is perfect for photorealistic scenery

[TERRAIN]

SWAP_WAIT_TIMEOUT=30

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

This variable is the number of frames that the terrain engine will wait for terrain textures to be loaded into video memory before forcing new tiles of terrain triangles to be rendered.

UseGlobalTerrainView=True

The default value is False.

Performance Tuning Tip:

By default, every camera has its own terrain view which requests texture and dem tiles near the camera to ensure that all cameras get a quality view of terrain. When tessellation is enabled, it is possible for cameras to share data and avoid the extra work required to manage multiple terrain views. For multi-view scenarios in which all views are near each other, it may be desirable to have views simply render the terrain tiles loaded by the default view. Setting this option to True will prevent all camera from creating a terrain view except for the default 3d view. This can help avoid texture flashing and terrain spikes that occur on some systems with multiple views and/or multiple video cards. This value can be overridden by the UseGlobalTerrainView entry in a given CameraDefinition allowing each camera to determine whether or not to create a terrain view. This setting will be engorged if Tessellation is not enabled.

[GRAPHICS]

SHADER_CACHE_VERSION=1

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

Using this rebuilds your shader cache by incrementing the number each time you make a change to the Prepar3D.cfg.

[JOBSCHEDULER]

AffinityMask=14

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

By default, Prepar3D will use all available processor cores. On machines with four or more cores, it will dedicate a core to rendering tasks. The easiest method for modifying the affinity mask is to open the windows calculator in programmer view, select the binary display mode, and flip the bits in the binary number displayed to select which cores the application should run on. Note that the cores are represented right to left.

[PANELS]

PANEL_MAX_UPDATE_PER_FRAME = 1

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

If 1, panels update no more than once a frame even if FPS drops below 18. This should not change the end result displayed unless update scripts rely on the 18hz timing to do stepwise simulation in a gauge script.

If 0 (default), update will get called more than once per frame if application framerate is lower than 18.

[MAIN]

FIBER_FRAME_TIME_FRACTION=0.33

Non-Default entry. This entry will not exist in your Prepar3D.cfg file by default and must be added to the file.

Performance Tuning Tip:

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", but it can cause stutters, and can also reduce the overall frame rate. Try reducing the number to the lowest level where you still get smooth scenery paging. This will vary depending on disk speed as well as the type of flying, as well as the selected scenery settings.