Multiplayer Shaking and Jitter

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Joined: Tue Dec 11, 2018 10:19 am

Multiplayer Shaking and Jitter

Postby =Jack= » Tue Dec 11, 2018 11:29 am

FSX and P3D have a limitation on updating another aircraft's position during multiplayer (default multiplayer, joinFS, etc.).

For example, if you are flying beside another aircraft in multiplayer and set your frame rate over 34, the other aircraft will shake and jitter all over the place. Set your frame rate below 34 and the other aircraft is smooth. It's obvious the simulator isn't capable of updating (sending or receiving) the user's positions fast enough.

This forces users that consistently have >34 fps to cap their frames at 34 to keep this from happening during multiplayer sessions. That's no good for form flying or VR.

I hope the development Team can look into this issue and see if anything can be done to fix it.

Thank you!

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Rob McCarthy
Lockheed Martin
Posts: 2878
Joined: Wed Aug 24, 2011 1:37 pm

Re: Multiplayer Shaking and Jitter

Postby Rob McCarthy » Wed Dec 12, 2018 1:16 pm


The default multiplayer update rates are relatively slow. These can be configured in the Multiplayer UI so updates are sent more often over the network. The learning center goes over these options here: ... rview.html

Rob McCarthy
Rob McCarthy
Prepar3D® Core Lead

Posts: 32
Joined: Tue Feb 21, 2012 4:17 pm

Re: Multiplayer Shaking and Jitter

Postby mchriest » Tue Mar 19, 2019 2:58 pm


Prepar3d v4.4.16 Professional
Windows 7 Pro
GeForce GTX 980

Player 1
Prepar3d v4.4.16 Professional Plus
Windows 10 Pro
GeForce RTX 2080

Local subnet (no routers, just a gigabit switch)
Firewall disabled

Experimenting with the demo "Multiplayer and SimOperator Base Scenario" (Host + 1 player over local net), I was maintaining a solid 60 fps on each machine, but experiencing the same judder issue. I attempted to resolve by increasing the update rate as indicated in Rob's solution. However as soon as I joined the multiplayer scenario, my frame rate on the joining machine (not the host) dropped from steady 60 fps to ~7 fps.
After shutting down P3D on both machines, I restarted, and re-hosted the scenario, this time disabling the high-frequency updates. Now, whenever joining the scenario my frame rate drops to 20-25 fps. This is repeatable.
If I reverse the machine's roles by hosting on the second machine, I have no drop in frame rate on either machine. So I have to assume that some configuration was set on my machine that is not undone when no longer using the high-frequency updates. Please help me find and reverse this.


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