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(updated September 13, 2014)

  Prepar3D Tweaks    
Fixing the Biggest Prepar3D Issues

This page covers some ways to improve Prepar3D performance, some details on the settings menu, how to customize the aircrafts' virtual cockpit views, and a few other tweaks that I have learned along the way.

Many of these suggestions were posted on forums by other users. My intent has been to just gather together all the tweaks in one place, where they can easily be viewed by anyone (without spending hours on the web searching).

Improving Performance:

Low Frame Rates: This is a major issue, mainly because so many users are trying to run P3D with settings that are way too high for their system. The first time that P3D runs after it is first installed, it sets your graphics, based on your system. Too many users immediately increase P3D's settings. Just because you can run the latest game with everything set to max, does not mean that you will be able to run P3D at max settings.

If you've noticed a major drop in FPS in v.2.3, during overcast conditions, this is likely due to a v.2.3 change that added a "volumizing visual effect to nearby clouds which does add a sample and a bit of math to the pixel shader."

Another issue was later discovered, which cause the clouds to be drawn twice as large as they should be. Thread on Prepar3D forums

Here are the two recommended fixes:
In your P3D installed directory, open the ShadersHLSL folder and then open Cloud.fx in a text editor (make a backup copy first).

1.) Find: GetScreenQuadPositions( quad, width, height );
Change it to: GetScreenQuadPositions( quad, width*0.5, height*0.5 );
If you're using an external weather engine like ASN, set the cloud density in P3D's weather setting as high as your system can handle. For ASN, a 'maximum' setting, with 'Live weather' mode results in the cloud coverage that is the closest to real weather conditions, but you may have to back this off some, if your FPS drop too low. I've been leaving it at maximum (going from normal to maximum only resulted in a small drop in FPS). I have ASN, set to 5 maximum cloud layers (which is default). Also make sure that you have "P3D low cloud offset" set to 0, as this doesn't work correctly with the 2.3 fix (according to HiFi) . . . enabling this will cause the (now correct, with the fix) bottoms of the clouds to be cut off, resulting in less cloud coverage.]

I found that the above fix totally restored my FPS, but if your FPS is still lower than what you had in v.2.2 in cloudy weather , try making the second edit (note that this one will may make clouds look slightly less realistic):
2.) Find: #define VOLUMIZE
And comment it out like this: //#define VOLUMIZE

You also need to clear your shaders cache by deleting the shader folder here:
\Users\USERNAME\AppData\Local\Lockheed Martin\Prepar3D v2

During heavy cloud cover, if your FPS is staying too low, disabled cloud shadows (plus you should keep Terrain Shadows disabled, due to the Terrain Shadow bug in v.2.3).

OOM (Out of Memory) issues: If you run out of VAS (Virtual Address Space), you run out of memory and P3D will crash to desktop. If you're running FSUIPC4, when your VAS gets below 300 MB, you will hear two Windows "exclamation" sounds. This is a warning that you are close to running out of VAS. This gives you time to save your flight before getting an OOM CTD. At this point, you should save your flight and exit P3D. Then, you can restart P3D, reload your flight, and continue flying. If this is happening frequently, then you need to reduce some P3D settings (like autogen density). There's also a Prepar3D.cfg edit , which may help to free up some memory.

P3D's maximum graphic settings are a LOT higher than what you have in FSX. For many sliders, 50% (midway) in P3D2 is about the same as 100% in FSX (for a similar setting), yet too many users expect to be able to use the same setting for P3D2 as they did for FSX (and then they get upset because their FPS drop to the basement).

P3D is still being optimized, and so are many of its third party add-ons. The other thing is that P3D was design not just for current hardware, but to take advantage of future hardware. So its graphic options can be set way higher than what most of our systems can effectively handle (the same is true for X-Plane 10). So we have to be a bit more conservative in the settings that we use. So even if you have a very high performance system, you will likely not be able to run P3D with everything set to max and still get high FPS when the graphics get the most demanding (such as landing at a major airport, in stormy weather . . . especially if you're using graphically demanding add-on scenery and/or an advanced aircraft).

For consistent frame rates: Do NOT set P3D's Target Frame Rate to Unlimited! Start out with a 20 to 30 FPS Target. If you frame rates are consistently remaining lower than your FPS Target, reduce your target amount (or reduce P3D's settings a bit). If they are consistently remaining higher, you can try increasing your Target FPS a bit. Once you have things set so that you're getting fairly consistent frame rates, save your settings. Note: I have different saved setting, depending on where I am flying (rural or urban) and on conditions.

One other thing that I have noticed is that you can often change a setting in P3D without seeing any difference in FPS . . . UNTIL you restart the sim. This is why it is so important to find the settings that work best and then stop messing with them, and just fly the sim.

If your Operating System is Win 8 and your joystick (or other USB controllers) is 'disappearing in P3D (reverts to just Mouse Yoke in Control settings). the proplem is that Win 8 is allowing your computer to power down your USB devices. This was constantly happening with my Saitek X52 Flight Control System (my LED display would also go dark). To fix this: in device manager, under Human Interface Devices (may be under USB Controllers, depending on your device), I right-clicked the "Saitek X52 Flight Controller (USB), selected Properties/Power Management, and unchecked "Allow the computer to turn off this device to save power."

Graphic Issues:
- NVidia GPUs: do NOT use the latest driver version! 340.52 breaks the tessellated terrain (NVidia is supposedly fixing this in their next driver release).
- Shaders folder: This folder can become corrupted and/or cluttered (especially when updating from a previous version), so when all else fails delete this folder (don't worry P3D will rebuild it when you run the sim). Path: \Users\"your user name"\AppData\Local\Lockheed Martin\Prepar3D v2

Use an External FPS Limiter:
This method can result in smoother, more consistent FPS, with less stutters. It is less necessary after updating to v.2.3, but it still improves things a bit for me. If your graphics card is an EVGA, run its Precision X overclocking software and enable FPS TARGET LIMITER (at the bottom) and set it to 30 FPS. Then in P3D Settings, set target FPS to Unlimited. The end result will be smoother, more consistent FPS, with less stutters. When your FPS drop below the targeted rate, your GPU's clock speed will automatically increase until the graphic load decreases (Note: this part also happens without using the FPS Limiter). I left all the other settings at default, since my GPU is a factory overclocked model . . . and overclocking requires caution, as you can damage your GPU.

- Make sure that you check "Start with Windows" in the software's configuration . . . and you have to enable the FPS Limiter every time (I have mine set in a Profile). Plus the software must remain open (or minimized) for the FPS Limiter to work.
- If your system is struggling to maintain 30 FPS (or your GPU is running too hot), reduce some P3D settings, or set the FPS Limiter to a smaller value.
- Alternate download for the Precision X overclocking software
- For MSI cards: MSI Afterburner 3.0.0 Download
-I don't have software links for  non-EGVA/MSI  cards, but you should be able to use the RTSS Rivatuner Statistics Server

The above only helps your frame rates when your GPU is struggling . . . in larger city areas, it is the AI and/or autogen and/or scenery complexity that are generally impacting your FPS, and these are mostly being processed by your CPU.

Also be aware that undocking a window (like ASN's weather radar) will pretty much cut your FPS in half, when you are using a FPS Limiter.

Scenario Startup Screen

Default Flight: To avoid possible issues, set up your default flight using one of the Prepar3D default aircraft (rather than an add-on aircraft).

Aircraft crashes when loading saved flight: When you have crashes enabled and the AI aircraft set to higher than 50%.  Your aircraft loads on top of an AI plane that had chosen that parking space Parking spaces are randomly occupied by AI aircraft. You can test this possibility by turning off crashes or setting your AI Aircraft level to 0. Another thing that could cause it is the occasional messed up AFCAD file, where the parking space is inside the crash zone of an object (try at a different starting location. like at a different gate).

Flying Tips (and setting up controls)

For the most Realism, use the following settings.

The following settings are the most important, if your want to fully follow the aircraft checklists, and be able to follow all my flight procedures:

- Make sure that "Enable automixture" is NOT checked, or you won't be able to manually adjust your Mixture.

Instrument's and lights: Make sure that "Display indicated airspeed" is checked.
Indicated Airspeed: the airspeed indicator measures the dynamic pressure of the outside air entering a pitot tube. At sea level, with an atmospheric pressure of 1013.2 mb, and with no wind effect, the airspeed indicated is the true speed of the aircraft relative to the surface. As the aircraft climbs, the air density decreases and the indicated speed will be less than the True Air Speed (TAS).  Your indicated airspeed is more importance than your true airspeed, because the flight characteristics of your aircraft are affected by atmospheric density. This is why control speeds are always given as KIAS (Knots Indicated Airspeed).

Flight controls: Make sure that Autorudder is NOT checked, or you will not be able to fully control the rudder independently.

Control Issue: When I first assigned the mixture and propeller controls to two of my Saitek axis, neither one gave a full range of adjustments. Instead I was limited to 19 to 81% (instead of 0 to 100%).
FIX: under the Controllers, Calibration tab, that if I change the default sensitivity from 64 to 127 (max), for both Propeller axis and Mixture axis, that now have full range!  I had not previously touched these settings, so is 64 actually the default setting?  If so, are others seeing these results as well?

Settings (and Some Fixes)

Below are my current settings, along with some explanations.

Graphic Global Settings/ Profile: I have several profiles saved, base on where I am flying (dense urban or sparse rural), conditions (stormy weather is much harder on FPS than clear/partly cloudy weather), and what add-ons I am using (flying in an Orbx region or one of there detailed airports can result in lower FPS than the default scenery).

Image and Texture Quality/FXAA: I found that enabling this actually makes things less sharp (because it 'softens' the image).

Frame Rate Controls:
- Target frame rate: I only have this set to "Unlimited" when I'm using an External FPS Limiter; at other times I generally have it set to 30 FPS.

View and Panel Settings:
- Wide-view Aspect Ratio:
I found that having this checked and using a 1.0 Zoom setting for most aircraft in Virtual Cockpit view, gives me the best flying perspective (making it easier to judge my landing distances). But with some  aircraft I have to zoom out a bit (even after moving my eyepoint back as far as I can), as I still felt like I was too close to the dash (but this is very much a matter of personal taste). NOTE: some users have posted that enabling  Wide-view Aspect Ratio, caused a drop in FPS, but this has no noticeable effect on my FPS.


Tessellation Factor: Tessellation moves most of the texture loading to the GPU (from the CPU), this is one of the biggest performance gains over FSX.  BUT you need to have a pretty good GPU, with at least 2GB of RAM to be able to run this at Max. If you set this higher than what your GPU can handle, you will likely notice graphic abnormalities, like flashing vertical black lines, along with an increase in stutters.

Mesh Resolution: I have this set on 5m, because Orbx add-on scenery is designed for 5m mesh. If I set this to a higher resolution (like 1m), some of my Orbx airports will have mesh issues (as in holes in runway).]

Testure Resolution: I have this set to 7cm, only because some of my Orbx scenery uses that resolution. If you're using only the default scenery, you can set this a few notches lower (without having any noticeable effect on your visuals).

Prepar3D adds Sundog software's dynamic waves, but water animations only appear at these Graphic Settings (and you have to be flying pretty low to see them):
1.) tessellation at Ultra
2.) Mesh at 5m or better [If using Orbx scenery, you should leave this at 5m (see note above)]
3.) Water quality at Ultra

Scenery Complexity: controls the amount of custom-made scenery objects in the scenery (as opposed to autogen objects ). Of all the scenery sliders, this one has the greatest impact on FPS (if you're using any custom scenery). This is one of the first sliders that I back off when I want to boost my FPS in an urban area.

- Cloud Shadow Cast Distance: Enabling this (setting it above 0) can have a major impact on FPS. I currently have this set to 80,000 . . . for some reason, this setting has less FPS impact than setting it to a lower setting (like 30,000).
- Terrain Shadow Cast Distance:
I currently have this set at 0 (disabled), as there is currently a bug in v.2.3 which can result in graphic issues if this is enabled (a v.2.3 patch is due out soon to fix this).
- Object Shadow Cast Distance:
Affects everything that is set to cast shadows that isn't terrain or clouds. With my above settings building shadows should be visible from 6000 meters away (~3.7 miles).

Object Type:
- Internal Vehicle:
"Cast" is unchecked in this screenshot, only because there is a bug in v.2.3 where enabling this does not stick.

Cloud detail: If you're using an external weather engine like ASN, set the cloud density in P3D's weather setting as high as your system can handle. For ASN, a 'maximum' setting, with 'Live weather' mode results in the cloud coverage that is the closest to real weather conditions, but you may have to back this off some, if your FPS drop too low. Since P3D v.2.3, I've been leaving it at maximum (going from normal to maximum only resulted in a small drop in FPS).

Simulation Settings: The :Rate at which weather changes over time" is disabled by the Active Sky Next weather engine.

In general, AI traffic has less of an impact in P3D than it does in FSX . . . but it still has an impact.

Road Vehicles: With default scenery, traffic will only appear on major highways (like US Interstates). [If you install FTX Global, traffic will appear on nearly all roads.]

Aircraft labels: I have this checked because it is often impossible to spot distant aircraft unless their label is also displayed. Being able to report seeing an aircraft that ATC is warning me about, is more important to me than turning of these unrealistic labels. If I had a larger/higher resolution monitor, I would not need this visual aid.

Real Time based on Time Zone (for flight location):
1.) Select a local airport, and under General Settings, check use System Time. Then Save the Flight, making it your default flight.
2.) To start a flight in a different time zone, either adjust the time for the Time Zone difference; or Load your above default flight and then select World/"Go to Airport" . . . the sim time will be reset to the (usually) correct time at the airport you move to. [Make sure that you do NOT check "Restore time on move".]

Editing CFG and XML Files

Important! Make sure that Prepar3D is not running, and make backup copies of the original files before making any edits!

cameras.cfg and flight.cfg
Path: C:\Users\"User Name"\AppData\Roaming\Lockheed Martin\Prepar3D v2

Changing Initial Virtual Cockpit Eyepoint:

Button 5 on my joystick is assigned to: "Look (reset to Forward view)," but I always had to tilt the view down to see my main instruments. But then I discovered that you can add a line to the Cameras.cfg that makes this my default forward view.

under [CameraDefinition.002]
added this line:
InitialPbh = 7,0,0
[Note: the above tilts the viewpoint down 7 degrees (which is what works best for me)]
The format is: p,b,h [p=pitch, b=bank and h=heading (Positive pitch makes the camera look down and positive heading makes the camera look right.)]

The above changes the Virtual Cockpit views for ALL aircraft. To change the Eyepoint for an individual aircraft:

Find the aircraft you want to edit.
Path: (under drive and directory where you install P3D):
\Lockheed Martin\Prepar3D v2\SimObjects\Airplanes\ (folder of aircraft you want to change)

under [Views]
find: eyepoint= -0.35, -0.85, 1.99 //(feet) longitudinal, lateral, vertical distance from reference datum
[Note: the values that follow "eyepoint=" will be different for each aircraft.]
Changing the first value (-0.35) moves the eyepoint forward or back.
Changing the second value (-0.85) moves the eyepoint left or right.
Changing the third value (1.99) raises or lowers the eyepoint.

For Example: if you want to sit a bit lower (lower your eyepoint), change the third value to a slightly lower value. [ For the example above, you might try changing the 1.99 value to 1.9, save your changes, and then check out your new viewpoint in the sim.]

*** When testing out your changes: Make sure that you Reset the Eyepoint (default is: CTRL+SPACE), since viewpoints are saved with the default flight (or whatever flight you loaded). Also make sure that you have the zoom set to your default amount.

Path: C:\Users\"User Name"\AppData\Roaming\Lockheed Martin\Prepar3D v2

To Reduce Blurry Scenery (from slow rendering):
Under: [MAIN]
Add: Fiber_Frame_Time_Fraction=0.33
[default is 0.33, so try a higher value, like 0.40 or 0.50]
From Prepar3D Learning Center/ Tuning Guide/ General Performance Guide: "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."
Arwen Note:
I'm currently using 0.40.

To reduce OOM (Out of Memory) issues:
Under: [MAIN]
Add: AlwaysFullLoad=1
[According to Beau at Lockheed Martin, this edit will force the terrain to unload and reload when resetting flights and changing locations, which can free up some memory. I've tried it and it did remove an OOM issue that I was having, when flying into one large urban airport (Heathrow).]

To Prevent Text Messages from Displaying:
Under: [Display]
Find the following and change the default "True" to "False" to prevent the specific text from displaying. Here are my changes:


To Increase Distance of Autogen Trees (and Orbx lights, most of which are labeled as trees):
Change to: AUTOGEN_TREE_MAX_DRAW_DISTANCE=12000.000000
[Note: use my above settings as a start, and reduce the draw distance if your FPS are dropping too much or you are now getting OOM issues. (12,000 appears to be the maximum distance).]

The following is no longer recommended after updating to version 2.3 of P3D:

To Reduce Stuttering, try changing the number of CPU cores that Prepar3D is using. There is no magical Affinity Mask setting that works best for every system. . . the value below is just what works for me.
[JOBSCHEDULER] (Note: you will likely need to create this heading.)
Add: AffinityMask=243
Arwen Note: the 243 value [Binary = 11110011] is for my Quad Core, 4770K CPU, with hyper threading enabled, but with Logical-1 and Thread-1 disabled. This is based on what Beau Hollis (Rendering System Lead - Prepar3D Team), suggested in this LINK; ". . . I don't think it considers a core open unless both HT cores are open. This is why masking off an entire core tends to help with stutters. We haven't done a lot of testing to back this up, but some initial findings suggest that you can leave open whichever core you choose. It might be better to use the first core and leave open a different core."
The value you need to use is specific to your computer's CPU (and depends hyper threading being enabled or disabled in your Bios). To figure out what value to use, try this Affinity Mask Calculator - [and use the Expert Mode].

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